Agricultural zoology

Dr. J. Ritzema Bos,

Lecturer In The Royal Agricultural College, Wageningen, Holland.

With An Introduction By

Eleanor A. Ormerod, F.R.Met.S., F.R.M.S., Etc.,

FORMERLY HON. CONSULTING ENTOMOLOGIST TO THE ROYAL AGRICULTURAL SOCIETY OF ENGLAND.

Translated By

J. R. Ainsworth Davis, B.A. (Trin. Coll. Camb.), F.C.P.,

PROFESSOR IN THE UNIVERSITY OF WALES, AND PROFESSOR OF BIOLOGY AND GEOLOGY IN THE SCIENTIFIC AND AGRICULTURAL DEPARTMENTS OF THE UNIVERSITY COLLEGE OF WALES.

With 149 Illustrations.

London: Chapman & Hall, LD. 1894

Author’S Preface.

The present volume of the Thaer Library was undertaken with the intention of providing agricultural colleges with a condensed review of the entire animal kingdom, but treating in greater detail the animals harmful or helpful to agriculture. I have, however, omitted all reference to the domesticated farm animals, as in all such institutions these are treated of, not by the zoologist, but by the lecturer on stock-breeding. Although the book is not allowed to exceed a certain size, I have taken great pains to make it intelligible, and venture to hope that it may be found suitable for the _private use of the practical farmer_. To the farmer who wishes more exhaustive information, and desires a reference book on the animal foes of agriculture, stock-breeding, horticulture, fruit-tree culture, and forestry, I venture to point out my larger work, _Animal Foes and Friends_,[1] brought out last year by the publisher of this book.

Footnote 1:

Tierische Schädlinge und Nützlinge für Ackerbau, Viehzucht, Wald- und Gartenbau. Lebensformen, Vorkommen, Einfluss und die Massregeln zu Vertilgung und Schutz. Praktisches Handbuch v. _Dr. J. Ritzema Bos_, Docent an der landwirtschaftl. Lehranstalt in Wageningen. Mit 477 eingedruckten Abbildungen. Preis 18 m., geb. 20 m. Verlag von Paul Parey, 10 Hedemannstrasse, Berlin, S.W.

It is hoped that the present volume may be found serviceable, both in the teaching of agricultural institutions, and to the practical farmer.

Dr. J. Ritzema Bos.

WAGENINGEN, _February, 1892_.

Translator’S Preface.

Agricultural education is making such rapid strides in this country, that no apology is needed for translating a book which appears to fill a gap, especially as it is written by a well-known authority. Dr. Ritzema Bos has kindly allowed certain small alterations to be made which adapt the work to the requirements of British agriculture. Additions are indicated by square brackets, and small print employed in the case of some non-British animals. A few forms have been omitted for similar reasons. Constant reference has been made to the published works of Miss E. A. Ormerod, who has added to my obligation by writing an Introduction, and I also wish to acknowledge my indebtedness to Mr. J. H. Salter, B.Sc., and Mr. J. Dawson Roberts, M.R.C.V.S., for kind help given by them.

J. R. Ainsworth Davis.

ABERYSTWYTH, _May, 1894_

Introduction.

By request of Professor Ainsworth Davis, the skilled translator of this “handy-book” on “Agricultural Zoology,” I add some words of introduction; and I have especial pleasure in so doing: not that any observations of mine can add value to the work of the well-known author, but because, having myself had the advantage for many years of colleagueship, and important help in my own work from the assistance of Dr. Ritzema Bos, I am well acquainted both with his extensive knowledge and also his scrupulous care in observation, and I believe that this abstract of his larger work, now given in a form in which it is available for general use, will meet a great need.

We have long wanted a book, plain in wording, and of moderate size, dealing with the wild animals or animal infestations generally which occur in connection with farm life—a manual, in fact, which, whilst suitable for the use of agricultural students and teachers, should at the same time not be too technically scientific to be intelligible to practical farmers or to general readers.

In the pages of the present volume a very serviceable amount of information will be found to be embodied. So far as can be arranged in the limited space the chief characteristics of the main divisions of the animal kingdom are given, from the _Vertebrata_—including descriptions of some of our most notable forms of what may be popularly described as beasts, birds, and reptiles,—to the _Arthropoda_, including information on a most serviceable amount of insect infestation; also regarding Mites, Ticks, etc. These are followed by the _Vermes_, including, among other families of the _Nematoda_, the eelworms which cause so much injury to crop growth; and these are followed by the intestinal tapeworms and the fluke.

The fourth sub-kingdom, that of _Mollusca_, includes, besides snails and slugs, various kinds of shell-fish; and the lower sub-kingdoms—including _Echinodermata_, which may be typified by starfishes and sea urchins, the _Cœlenterata_, or Zoophytes, and the _Protozoa_—will be found to be just entered on sufficiently to show their place in the scale.

The clear descriptions, made still more instructive by the numerous and good figures, will speak for themselves to all readers; but I should like to add a few lines to point out the serviceableness of a handbook in which the reader may turn at pleasure to the history of any common farm animal—as a weasel or a vole, a wood-pigeon or a pheasant, a blindworm or a common frog. And, in regard to the insect infestations, to which it will be seen more than a hundred pages of the book are devoted, I can bear witness to the great amount of valuable information which I constantly derive myself from the study of the writings of Dr. Ritzema Bos on this subject; and I trust this little manual of “Agricultural Zoology” may take the place in our farm and school libraries which I believe it to be excellently fitted to fill.

ELEANOR A. ORMEROD, _Late Consulting Entomologist of the Royal Agricultural Society of England_.

TORRINGTON HOUSE, ST. ALBAN’S, _May 24, 1894_.

Contents.

PAGE INTRODUCTION— I. Subdivision of the Animal Kingdom 1 II. Review of the Structure and Vital Phenomena of Animals 3–16

=First Sub-Kingdom: VERTEBRATA (Backboned Animals)= 16–82 CLASS I: MAMMALIA (Sucklers) 21–48 ORDER: Carnivora (Beasts of Prey) 24–30 Family: Felidæ (Cat Family) 24–25 Family: Canidæ (Dog Family) 25–26 (Wolf, p. 25; Fox, p. 26.) Family: Mustelidæ (Weasel Family) 26–30 (Martens and Polecat, p. 26; Ferret, p. 27; Stoat and Weasel, p. 28; Mink, Otter, and Badger, p. 29.) ORDER: Insectivora (Insect-eating Mammals) 30–33 (Shrews, pp. 30, 31; Mole, pp. 31–33; Hedgehog, p. 33.) ORDER: Cheiroptera (Bats) 33–35 ORDER: Rodentia (Gnawing Mammals) 35–43 Family: Leporidæ (Hares and Rabbits) 36–38 (Hare and Rabbit, p. 37.) Family: Muridæ (Mouse Family) 38–41 (Hamster, Black Rat, and Brown Rat, p. 39; Common Mouse, Long-tailed Field Mouse, and Harvest Mouse, p. 40; Corn Mouse, p. 41.) Family: Arvicolidæ (Vole Family) 41–43 (Bank Vole and Water Vole, p. 42; Field Vole, pp. 42, 43; Southern Field Vole, p. 43.) ORDER: Ruminantia (Cud-chewing Mammals) 44–47 Family: Cervidæ (Deer Family) 45–47 (Red Deer, p. 46; Roebuck and Fallow Deer, p. 47.) ORDER: Multungula or Pachydermata (Many-hoofed or Thick-skinned Mammals) 48 (Wild Boar, p. 48.) ORDER: Solidungula (Single-hoofed Mammals) 48 CLASS II: AVES (Birds) 49–74 ORDER: Raptores (Birds of Prey) 53–55 ORDER: Scansores (Climbing Birds) 55–56 (Cuckoo, pp. 55, 56.) ORDER: Passeres (Perching Birds) 57–65 Group: Hirundinidæ (Swallows) 57–58 (Swallows and Martins, p. 57; Swift and Goatsucker, p. 58.) Group: Magnirostres (Large-beaked Perchers) 58–61 (Jackdaw, Crows, Rook, and Raven, pp. 59–61; Magpie and Jay, p. 61.) Group: Conirostres (Conical-beaked Perchers) 61–64 (Titmice, Larks, and Buntings, pp. 61, 62; Finches, p. 62; Sparrows, pp. 62, 63; Linnet, p. 63; Chaffinch, pp. 63, 64.) Group: Subulirostres (Awl-beaked Perchers) 64–65 (Wagtails, Pipits, and Hedge “Sparrow,” p. 64; Warblers, pp. 64, 65; Thrush-like birds, p. 65.) ORDER: Gyrantes (Doves) 65–67 (Wood Pigeon, pp. 66, 67; Turtle Dove and Rock Pigeon, p. 67.) ORDER: Rasores (Poultry) 67–68 (Pheasant, p. 68.) ORDER: Grallatores (Wading-Birds) 68–70 ORDER: Natatores (Swimming-Birds) 70–74 Family: Lamellirostra (Ducks) 71–73 Family: Longipennes (Gulls) 73–74 CLASS III.: REPTILIA (Reptiles) 74–79 CLASS IV.: AMPHIBIA (Amphibians) 79–81 CLASS V.: PISCES (Fishes) 81–82

=Second Sub-Kingdom: ARTHROPODA (Jointed-limbed Animals)= 82–206 CLASS I.: INSECTA (Insects) 85–194 ORDER I.: Coleoptera (Beetles) 94–118 Family: Carabidæ (Ground Beetles) 94–96 (Corn Ground Beetle, pp. 95, 96.) Family: Staphylinidæ (Rove Beetles) 96–97 Family: Silphidæ (Burying Beetles) 97 (Black Burying Beetle, and Beet Carrion Beetle, p. 97.) Family: Nitidulidæ (Shine Beetles) 97–98 (Turnip-flower Beetle, pp. 97, 98.) Family: Cryptophagidæ (Secret-eating Beetles) 98–99 (Beet Beetle, pp. 98, 99.) Family: Lamellicornia (Chafers) 99–102 (Cockchafer, pp. 100, 101; Buckwheat Beetle, p. 101; Rye and Garden Chafers, p. 102.) Family: Elateridæ (Click Beetles) 102–105 (“Wireworms,” pp. 103–105.) Family: Curculionidæ (Weevils) 105–110 (Seed Beetles, pp. 106, 107; Pea Weevil, pp. 107, 108; Mouse-tooth Weevils, p. 108; Gall Weevils, pp. 108–110.) Family: Chrysomelidæ (Leaf Beetles) 110–117 (Colorado Beetle, pp. 111–113; Tortoise Beetles, pp. 113, 114; Flea Beetles, 114–117.) Family: Coccinellidæ (Lady Birds) 117–118 ORDER II.: Orthoptera (Straight-winged Insects) 118–121 (Migratory Grasshopper, pp. 119, 120; Mole Cricket, pp. 120, 121.) ORDER III.: Neuroptera (Net-winged Insects) 121–123 (Dragon Flies, p. 122; Lace Flies, pp. 122, 123; Scorpion Flies, p. 123.) ORDER IV.: Hymenoptera (Membranous-winged Insects) 123–136 Family: Apidæ (Bees) 125–126 Family: Vespidæ (Wasps) 126–128 Family: Fossores (Digging Wasps) 128–129 Family: Formicidæ (Ants) 129–132 Family: Ichneumonidæ (Ichneumon Flies) 132–134 Family: Tenthredinidæ (Saw-flies) 134–136 (Turnip Saw-fly, pp. 134–136.) ORDER V.: Lepidoptera (Butterflies and Moths) 136–159 Family: Diurna (Butterflies) 137–142 (Whites, pp. 138–142.) Family: Noctuidæ (Owlet Moths) 142–152 (Surface Caterpillars, p. 143; Dart or Turnip Moth, pp. 143–145; Cabbage Moth, pp. 145–147; Lettuce and Pea Moths, p. 147; Grass-root Moth, p. 148; Couch-grass Moth, pp. 148, 149; Wheat-haulm Moth, p. 149; Grass Moth, pp. 149, 150; Darnel Moth, p. 150; Silver Y Moth, pp. 151, 152.) Family: Pyralidæ (Snout Moths) 152–155 Family: Tortricidæ (Leaf-rollers) 155–157 (Fawn-coloured Pea Moth, p. 156; Crescent Pea Moth, pp. 156, 157.) Family: Tineidæ (Leaf-miners) 157–159 (Carrot Moth, pp. 157, 158; Diamond-back Moth, pp. 158, 159.) ORDER VI.: Hemiptera (Half-winged Insects) 159–163 Family: Aphidæ (Plant Lice) 159–163 ORDER VII.: Physopoda (Bladder-footed Insects) 163–164 (Thrips, pp. 163, 164.) ORDER VIII.: Diptera (Flies) 164–193 Family: Culicinæ (Gnats) 164–165 Family: Gallicolæ (Gall Gnats) 165–170 (Hessian Fly, pp. 166–168; Scarlet Wheat Midge, pp. 168, 169; Wheat Midge, 169, 170.) Family: Rostratæ (Crane Flies) 170–172 Family: Muscæformes (Gnat Flies) 173–174 (Sand Flies, pp. 173, 174.) Family: Tabanidæ (Gad Flies) 174 Family: Muscidæ (True Flies) 175–184 (Caterpillar and Flesh Flies, p. 175; Common Flies, p. 175; Flower Flies, pp. 176, 177; Cheese-fly, p. 178; Ribbon-footed Corn Fly, pp. 178–182; Frit Fly, pp. 182–184.) Family: Syrphidæ (Hover Flies) 185 Family: Stomoxydæ (Stable Flies) 185–186 Family: Œstridæ (Bot Flies) 186–192 (Ox Warble-fly, pp. 186–188; Sheep Bot Fly, pp. 188–190; Horse Bot, etc., pp. 190–192.) Family: Pupipara (Louse Flies) 192–193 ORDER IX.: Aphaniptera (Fleas) 193 ORDER X.: Parasita (Lice) 193–194 CLASS II.: MYRIOPODA (Centipedes and Millipedes) 195 CLASS III.: ARACHNOIDEA (Scorpions, Spiders, Mites) 195–205 ORDER: Acaridea (Mites) 196–202 Family: Acaridæ (True Mites) 196–202 (Itch or Mange Mites, pp. 196–202.) Family: Ixodidæ (Ticks) 202–204 Family: Gamasidæ (Beetle Mites) 204 (Fowl Mite, p. 204.) Family: Trombidiidæ 205 (Plant Mite or “Red Spider,” p. 205.) CLASS IV.: CRUSTACEA (Crustaceans) 206

=Third Sub-Kingdom: VERMES (Worms)= 206–245 CLASS: ANNELIDA (Segmented Worms) 207–209 (Earthworms, pp. 207–209.) CLASS: NEMATELMINTHES (Round Worms) 209–231 ORDER: Nematoda (Thread Worms) 210–231 Family: Strongylidæ (Palisade Worms) 212–215 Family: Trichotrachelidæ (Whip Worms) 215–218 (Trichina, pp. 216–218.) Family: Filaridæ (Slender Thread Worms) 218 Family: Ascaridæ (Round Worms) 218–219 Family: Anguillulidæ (Eelworms) 219–231 (Stem Eelworm, pp. 220–224; Wheat Eelworm, pp. 224–227; Beet Eelworm, pp. 227–230; Root-knot Eelworm, p. 231.) CLASS: PLATYHELMIA (Flat Worms) 231–245 ORDER: Cestoda (Tapeworms) 231–240 ORDER: Trematoda (Flukes) 240–245

=Fourth Sub-Kingdom: MOLLUSCA (Mollusca)= 245–251 CLASS: CEPHALOPODA (Cuttlefishes) 247 CLASS: GASTROPODA (Snails and Slugs) 247–251 (Grey Field Slug, pp. 249–251.) CLASS: LAMELLIBRANCHIATA (Bivalve Molluscs) 251

=Fifth Sub-Kingdom: ECHINODERMATA (Hedgehog-skinned Animals)= 252–253

=Sixth Sub-Kingdom: CŒLENTERATA (Zoophytes)= 253–255

=Seventh Sub-Kingdom: PROTOZOA (One-celled Animals)= 255–256

Illustrations.

FIG. PAGE 1. Schematic Longitudinal Section of the Human Body 4 2. Human Skeleton 7 3. Skeleton of an Ox 9 4. Bending of the Arm by Contraction of the Biceps Muscle 10 5. Diagram to explain the Action of the Motor and Sensory Nerves 11 6. Diagram of the Course of the Circulation 13 7. Life History of the Small-winged Gall-fly (_Andricus terminalis_) 15 8. Diagram of a Fish’s Heart 18 9. Diagram of a Mammal’s Heart 20 10. Diagram of a Reptile’s Heart 20 11. Diagram of a Frog’s Heart 21 12. Vertical Section of a Human Grinding Tooth 22 13. Crown of an Ox’s Grinder 22 14. Skull of Domestic Cat 25 15. Pine Marten (_Mustela martes_) 27 16. Skull of Mole 30 17. Common Shrew (_Sorex vulgaris_) 31 18. Skeleton of Bat 34 19. Skull of Squirrel 35 20. Abnormal Tooth in Hare 37 21. Hamster (_Cricetus frumentarius_) 38 22. Long-tailed Field Mouse (_Mus sylvaticus_) 40 23. Upper Back Teeth of Brown Rat 41 24. Upper Back Teeth of Water Vole 41 25. Southern Field Vole (_Arvicola arvalis_) 43 26. Skull of Sheep 44 27. Development of Roebuck Antlers 45 28. Wing of Buzzard 50 29. Section through Bird’s Egg 51 30. Eagle Owl (_Otus maximus_) 52 31. Head and Foot of Falcon 53 32. Golden Eagle (_Aquila chrysaëtus_) 54 33. Barn Owl (_Strix flammea_) 55 34. Cuckoo (_Cuculus canorus_) 56 35. Goatsucker (_Caprimulgus europæus_) 58 36. Head of Rook (_Corvus frugilegus_) 60 37. Head of Bullfinch (_Pyrrhula vulgaris_) 62 38. Nightingale (_Daulias luscinia_) 65 39. Wood Pigeon (_Columba palumbus_) 66 40. Capercailzie (_Tetrao urogallus_) 68 41. Pheasant (_Phasianus colchicus_) 69 42. Woodcock (_Scolopax rusticola_) 70 43. Crested and Little Grebes (_Podiceps cristatus and minor_) 71 44. Grey Goose (_Anser cinereus_) 72 45. Herring Gull (_Larus argentatus_) 74 46. Common Lizard (_Lacerta agilis_) 75 47. Adder (_Pelias berus_) 76 48. Grass Snake (_Tropidonotus natrix_) 77 49. Blindworm (_Anguis fragilis_) 78 50. Great Crested Newt (_Triton cristatus_) 79 51. Common Frog (_Rana temporaria_) 80 52. Natterjack (_Bufo calamita_) 81 53. The Perch (_Perca fluviatilis_) 82 54. Wood-borer (_Sirex_) 83 55. Centipede (_Scolopendra morsitans_) 84 56. Ground Beetle, showing Nervous System 84 57. Disarticulated Grasshopper 85 58. Head and Mouth-parts of a Ground Beetle 87 59. Leg of Ground Beetle 88 60. Stages of Silkworm Moth (_Bombyx mori_) 88 61. Stages of Hornet (_Vespa crabro_) 89 62. Migratory Grasshopper (_Acrydium migratorium_) 90 63. Looper Caterpillar 90 64. False Caterpillar 90 65. Stages of Cockchafer (_Melolontha vulgaris_) 91 66. Larva of a Weevil 92 67. Stages of Aphis-eating Fly (_Syrphus pyrasti_) 92 68. A Ground Beetle (_Carabus auronitens_) 95 69. Corn Ground Beetle (_Zabrus gibbus_) and larva 95 70. A Rove Beetle (_Staphylinus erythropterus_) 96 71. Black Burying Beetle (_Silpha atrata_) and larva 96 72. Antennæ of Cockchafer 99 73. Abdomens of Common and Horse-chestnut Cockchafers 100 74. Skipjack (_Agriotes lineatus_) 102 75. Skipjack about to spring 103 76. Grain-plants sown deep and shallow, to show Wireworm attack 104 77. Bean Beetle (_Bruchus rufimanus_) 106 78. Pea Weevil (_Sitones lineatus_) 107 79. Mouse-tooth Weevil (_Baridius chloris_) and larva 108 80. Turnip Gall Weevil (_Ceutorhynchus sulcicollis_) 109 81. Colorado Beetle (_Chrysomela decemlineata_) 111 82. Stages of Colorado Beetle 112 83. Cloudy Tortoise Beetle (_Cassida nebulosa_) 113 84. Rape Flea Beetle (_Psylliodes chrysocephalus_) 114 85. Stages of Seven-spotted Lady-bird (_Coccinella septempunctata_) 118 86. Stages of Common Lace Fly (_Chrysopa vulgaris_) 122 87. Head of Honey Bee (_Apis mellifica_) 124 88. Common Wasp (_Vespa vulgaris_) and nest 127 89. Common Sand Wasp (_Ammophila sabulosa_) 129 90. Stages of Yellow-legged Ichneumon Fly (_Microgaster glomeratus_) 133 91. Turnip Saw-fly (_Athalia spinarum_) and caterpillars 135 92. Head of Butterfly 136 93. Scales from Butterfly’s Wing 136 94. Stages of Peacock Butterfly (_Vanessa io_) 138 95. Stages of Cabbage White (_Pieris brassicæ_) 139 96. Garden White (_Pieris rapæ_), male 141 97. Garden White, female and caterpillar 141 98. Green-veined White (_Pieris napi_) 142 99. Dart or Turnip Moth (_Agrotis segetum_) and caterpillar 143 100. Stages of Cabbage Moth (_Mamestra brassicæ_) 146 101. Grass Moth (_Charæas Graminis_) and caterpillar 150 102. Stages of Silver Y Moth (_Plusia gamma_) 151 103. Hop Snout Moth (_Hypena rostralis_) 153 104. Mother-of-Pearl Moth (_Botys margaritalis_) and larva 155 105. Fawn-coloured Pea Moth (_Grapholitha nebritana_) 156 106. Larch Moth (_Coleophora laricella_) 157 107. Wings of a Bug 159 108. Bean Aphis (_Aphis papaveris_) 160 109. Corn Thrips (_Thrips cerealium_) 163 110. Wheat Midge (_Cecidomyia tritici_) 165 111. Barley attacked by Hessian Fly 167 112. Larvæ of Wheat Midge (_Cecidomyia tritici_) 169 113. Stages of Daddy Longlegs (_Tipula oleracea_) 171 114. Rain Breeze Fly (_Hæmatopota pluvialis_) 174 115. Caterpillar Fly (_Tachina fera_) 175 116. Turnip infested by Cabbage Fly (_Anthomyia brassicæ_) 177 117. Ribbon-footed Corn Fly (_Chlorops tæniopus_) 179 118. Stages of ditto 181 119. Wheat Plant distorted by winter generation of ditto 181 120. Stages, etc., of Frit Fly (_Oscinis frit_) 183 121. Stages of Horse Bot Fly (_Gastrus equi_) 190 122. Horse Louse (_Hæmatopinus macrocephalus_) 194 123. Common Snake Millipede (_Julus terrestris_) 195 124. A Spider (_Salticus scenicus_) 196 125. Mange Mite of the Pig (_Sarcoptes scabiei, var. suis_) 197 126. Ditto 198 127. The Dog Tick (_Ixodes ricinus_) 203 128. Diagrammatic transverse section through a Thread Worm 210 129. Tail of male _Strongylus armatus_ 213 130. Encapsuled Muscle Trichinæ in flesh 217 131. Male Intestinal Trichina 217 132. Rye Plant in the later stage of the Eelworm Disease 222 133. Ear Cockles of Wheat 225 134. Stages of Beet Eelworm (_Heterodera Schachtii_) 226 135. _Tænia saginata_ 232 136. Common Tapeworm (_Tænia officinalis_) 234 137. Tapeworm Larva (_Tænia solium_) 234 138. Types of Bladder-worm 235 139. Measle of _Tænia solium_ 235 140. Measles in Pork 236 141. Liver Fluke (_Distoma hepaticum_) 241 142. Life History of Liver Fluke 242 143. Diagrams of Molluscs 246 144. Grey Field Slug (_Limax agrestis_) 249 145. Common Starfish (_Asterias rubens_) 252 146. Freshwater Polype (_Hydra_) 254 147. A Jellyfish (_Pelagia noctiluca_) 254 148. A Sea Anemone (_Sagartia nivea_) 254 149. Proteus Animalcule (_Amœba_) 255

Zoology.

Introduction.

I. Subdivision of the Animal Kingdom.

There are animals so like one another that they are given the same name. Such animals are ranked in the same _species_. Animals which differ so much that they have to be referred to different species, but which notwithstanding agree in the majority of their characters, especially the most important ones, are placed in the same _genus_. Hare and rabbit, or horse and donkey, are reckoned as different species of the same genus. Genera resembling one another are united into a _family_; thus, the pine marten and the beech or stone marten both belong to the _Marten genus_ (Martes), while the weasel and stoat are different species of the _Weasel genus_ (Mustela); but these two genera are so similar that they are both placed in the same family, _i.e._ the _Weasel family_ (Mustelidæ). Nearly related families together build up an _order_. Thus, the Weasel family, Dog family, Cat family, etc., collectively constitute the _order of Carnivora_, characterized, speaking generally, by the same kind of teeth, claws, habits, and food. Several related orders are united into a _class_. Thus, for example, carnivorous animals (Carnivora), ruminating animals (Ruminantia), gnawing animals (Rodentia), etc., constitute different orders of the _class of Sucklers_ (Mammalia); while birds of prey (Raptores), pigeons (Gyrantes), and poultry (Rasores), are included in a second class, that of _Birds_ (Aves). But both Birds and Mammals have a skeleton, of which the chief support is the backbone; on this account they are placed in a larger subdivision, the _sub-kingdom_ of Backboned animals (Vertebrata); while snails are grouped under the sub-kingdom of _Molluscs_, millipedes and centipedes under that of _Jointed-limbed animals_ (Arthropods).

In this way the animal kingdom is divided into _sub-kingdoms_, the sub-kingdoms into _classes_, the classes into _orders_, the orders into _families_, the families into _genera_, and the genera into _species_. Animals of the same species which differ from one another in more or less constant characters, belong to different _races_ (domestic or geographical races).

There are many species of animals the external features of which are well known to ordinary folk, and which therefore possess a definite English name, but a much larger number, of the smaller forms especially, have no English name. It is, therefore, necessary to devise new names for these species. The English names, however, are liable to cause great confusion, since in different districts the same name is often applied to widely different animals. Besides this, distinct names have usually been given to successive stages in the life history of the same form: “wireworms,” for example, are the young state of the “click beetle.”

By using the scientific method of naming invented by Linnæus, confusion is made impossible. The Latin names of this naturalist have the great advantage that they not only give a perfectly distinct name to any particular species, but also at the same time show the genus to which it belongs. Each kind of animal possesses, in fact, two names; just in the same way as every person possesses at least two names, a Christian name and a surname. The generic name comes first, and is, of course, common to all animals of the same genus. The second name is the specific one, and belongs exclusively to animals of the same species. The hare and rabbit, for example, are both included in the genus _Lepus_. The Latin name of the first is _Lepus timidus_; that of the second, _Lepus cuniculus_. Horse = _Equus caballus_; ass = _Equus asinus_.

II. Review of the Structure and Vital Phenomena of Animals.

I select as a point of departure the human body, and the bodies of domestic animals, because my readers are best acquainted with these.

The limbs consist, beginning on the outside, of skin, flesh, and bone. The same parts can also be distinguished in the head, neck, and trunk; but in these divisions of the body they enclose a cavity, the _body-cavity_, which, again, contains various parts (“organs”), which are not everywhere attached to the body-wall. Fig. 1 represents a longitudinal section through the body. The skin is represented by a line, flesh and internal lining are shaded, while the bones are black. These parts form together the _body-wall_. In front the body-wall encloses a cavity, the body-cavity (_Kh._), which in Mammals is divided into two sections (thoracic cavity, _Bz.h_, and abdominal cavity, _B.h._) by the _midriff_ (diaphragm). In the thoracic cavity are found the lungs and heart (_H_), also most of the gullet or upper part of the gut; the abdominal cavity contains the remainder of the often much-coiled gut, which in one place widens into the stomach (_M_), also the kidneys, spleen, and parts connected with the gut (_e.g._ the liver). The cavities are bounded behind by the backbone (vertebral column), which is made up of many flattened vertebræ. The uppermost vertebra supports the skull, which encloses a _cranial cavity_ (_Sch.h._) continuous with a _vertebral canal_ bounded by the vertebræ. Cranial cavity and vertebral canal form together a second body-space, in which are contained the brain and spinal cord.

[Illustration:

FIG. 1.—Schematic Longitudinal Section of the Human Body. ]

We will now consider the individual parts of the body, beginning with the _skeleton_. The axis of the skeleton is formed by the vertebral column (spine), which is composed of flat bones, the _vertebræ_. A vertebra usually consists of (1) the body, which occupies the front; (2) the arch, which possesses several projections or processes (neural spine, transverse processes, articular processes) and encloses the vertebral canal (_W.h._). All mammals have seven neck or cervical _vertebræ_ (Fig. 2, 1); while the number of the remaining vertebræ varies according to the species. The cervical vertebræ, which support the head, are followed by the dorsal or _thoracic vertebræ_ (12 in man, Fig. 2, 2), and these by the strong loin or _lumbar vertebræ_ (5 in man, Fig. 2, 3). Cervical, thoracic, and lumbar vertebræ are movable, but, in man, the last-named are followed by five vertebræ immovably united together to make up the _sacrum_, and these again by tail- or _caudal vertebræ_. Man has four such vertebræ, all poorly developed, and fused with one another (Fig. 2, 5); but in many animals there are a large number, movably united to make up a tail.

The ribs, which in mammals bound the chest, are jointed to the thoracic vertebræ. Man has 12 pairs of ribs; each rib consists of a bony part behind and a gristly (cartilaginous) part in front. The so-called true ribs (Fig. 2, 14) [the upper pairs] are movably united with the breast-bone, but this is not the case with the false ribs (Fig. 2, 15).

In the head we distinguish the brain-case or _cranium_, and the skeleton of the _face_. The first contains the cranial cavity in which the brain is enclosed. We distinguish—2 frontal bones (fused together in man, Fig. 2, 6); 2 parietal bones (7); 2 temporal bones (8); an occipital bone (9) composed of several pieces fused together, perforated by the foramen magnum [where brain and spinal cord unite], and bearing two elevations or condyles [for effecting union with the backbone]; and the sphenoid and ethmoid bones which make up the base of the cranium. The facial skeleton consists of the framework of the jaws and palate, and, together with some of the cranial bones, bounds the cavities in which the eyes are contained (orbits), and the nasal cavities. It consists of the maxillary bones (Fig. 2, 12), the premaxillary bones (Fig. 3, 7,—in man these 4 bones are fused together into one piece), the nasal bones, the lachrymal bones, the ploughshare bone (vomer), the turbinated bones, the cheek-bones (or malars, Fig. 2, 11), the palate-bones, and the lower jaw (Fig. 2, 13). (The last originally consists of two symmetrical halves.)

The upper and lower limbs are built on the same type, and therefore consist of corresponding parts (cp. Fig. 2). The more similar the functions of the two pairs, the closer their resemblance. In the ox they are much more alike than in man; in the bird, on the contrary, the similarity is much less. A distinction can be drawn in both limbs between the bony girdles (shoulder-girdle and hip-girdle), which serve for union with the trunk-skeleton, and the different subdivisions of the limbs themselves. I place side by side the parts of the arm and leg of man.

ARM. │ LEG. I. Shoulder-girdle, consisting │ I. Hip-girdle, consisting of: of: │ Shoulder-blade (Scapula) (Fig.│ Hip-bone (Ilium) (24). 2, 17). │ Collar-bone (Clavicle). │ Pubis. Coracoid process (of Scapula).│ Rump-bone (Ischium). II. Upper arm: │ II. Thigh: Upper arm-bone (Humerus) (18).│ Thigh-bone (Femur) (25). III. Fore arm: │III. Leg: Radius (19). │ Shin-bone (Tibia) (26). Ulna (20). │ Clasp-bone (Fibula) (27). IV. Hand: │ IV. Foot: Two rows of wrist-bones │ Two rows of ankle-bones (Carpal bones) (21). │ (Tarsal bones) (28). Metacarpal bones (22). │ Metatarsal bones (29). Finger-bones (Phalanges) (23).│ Toe-bones (Phalanges) (30).

The differences between arm and leg are explained by their different uses. The bones of the leg, used to support the human body, are firmer and thicker, but less movable than those of the arm, which is employed in grasping. Consequently the union between the hip-girdle and the trunk-skeleton is firmer than that of the shoulder-girdle. The radius can rotate upon the ulna, so as to completely turn the hand over; a similar twisting of the foot would not be of use, and cannot be effected. The leg has a knee-pan (patella) (Fig. 31), with which there is no bone in the arm to correspond. In the foot the toes are short, and the remaining parts long; for instance, one of the tarsal bones, the calcaneum (heel-bone), is strongly developed and projects behind (28*). In the hand, the digits are relatively long, and since the tip of the thumb can be made to touch the tips of all the fingers, are admirably adapted for grasping.

[Illustration:

FIG. 2.—The Human Skeleton. ]

The number of fingers or toes is at most five, but may be less. The horse has a single digit to each limb; the ox, two well developed and two remaining as rudiments; the pig, two large and two small; while the dog has four toes in the hind foot, five in the fore foot.

Man walks on the sole of the foot. Some other animals (dog, cat) on the toes; others again (horse, ox, pig), on the tips of the toes. In the last case there is not simply a horny structure (nail or claw) on the upper side of the toe, but a hoof sheathing the whole of its tip. In many animals the thigh and upper arm are drawn close up to the body, so that the limbs appear quite different from those of man. (Compare Fig. 2 with Fig. 3.)

[Illustration:

FIG. 3.—Skeleton of an Ox. I. _Skull_: 1, Frontal bone, with horn cores, _a_; 2, temporal bone; 3, malar or cheek-bone; 4, maxillary bone; 5, lachrymal bone; 6, nasal bone; 7, premaxillary bone; 8, lower jaw; 9, orbit; 10, occipital bone. II. _Neck and Trunk_: _H_, 7 cervical vertebræ; _R_, 13 thoracic vertebræ; _L_, 6 lumbar vertebræ; _K_, sacrum; _Su_, caudal vertebræ; _C_, 13 pairs of ribs; _D_, sternum. III. _Fore Limbs_: _Sc._, scapula; _A_, humerus; _S_, radius; _E_, ulna; _U_, carpus; _M_, metacarpals; i., ii., iii., phalanges. IV. _Hind Limbs_: _B_, hip-girdle, _a_, ilium, _b_, ischium; _F_, femur; _P_, patella; _T_, tibia; _Sp_, tarsus; _M_, metatarsals; i., ii., iii., phalanges. ]

The bones are usually surrounded by flesh. This consists of a number of different pieces united together by a delicate, elastic, fibrous mass (connective tissue). The different pieces are termed _muscles_, each of which is again made up of a large number of muscle-fibres, all taking a longitudinal direction. Each fibre can contract, and a muscle becomes shorter and thicker by simultaneous contraction of all its fibres. The contraction and subsequent relaxation of muscles move other parts. There are some muscles, the _hollow muscles_, which surround a cavity, and by their contraction propel the liquid or solid substances found in their cavity. The heart, for example, is a large muscle of this sort, serving to propel the blood, while the hollow muscular coat of the gut moves on the contained food. Other muscles are fixed by their ends to other parts of the body, which they move by their contraction. We distinguish between _dermal muscles_ and _skeletal muscles_, attached respectively to the skin or by one end to an integumentary structure (hair, feather, scale), and to parts of the skeleton. The animals which are devoid of any internal skeleton, the _invertebrates_ (_i.e._ all animals except vertebrates), naturally possess no skeletal muscles. Examples of _dermal muscles_ are those by means of which a bird erects its feathers (tail-coverts of peacock!), and those which enable a hedgehog to roll itself into a ball and stick out its spines. Each end of a _skeletal muscle_ is connected with a bone. If such a muscle contracts the more easily movable bone is drawn towards the less easily movable one (Fig. 4). In order that the bones may be movable upon one another they are united together by joints.

According as muscular movements are, or are not, under the influence of the will, they are distinguished as _voluntary_ and _involuntary_. To the latter kind belong the movement of the heart, and the movements of the muscles in the wall of the gut by which the food is made to progress.

[Illustration:

FIG. 4.—Bending of the Arm by Contraction of the Biceps Muscle. _a_, humerus; _b_, ulna; _c_, elbow-joint; _d_, biceps muscle; _e_, origin; _f_, insertion of the same. In the right-hand figure of the muscle _d_ is contracted; in the left-hand figure it is slackened. ]

To destroy the contractile power of a muscle it is not necessary to injure the muscle itself. Every muscle is related to a nerve, which sends its fine branches to the fibres making up the muscle. If we cut the nerve, the corresponding muscle loses its power of contraction. But the nerve arises from the _central nervous system_, which in vertebrates principally consists of the brain and spinal cord. The muscle will therefore lose its contractile power if the connection with these central parts is broken. The true cause of movement resides in these parts. A sort of change, the essential nature of which is unknown to us, takes place in them, and is propagated along the nerve to the muscle, causing it to contract. The central nervous system is, therefore, the origin, the centre from which the order to contract proceeds; hence its name. The nerves which run from these central parts to the muscles are known as the _nerves of movement_ (motor nerves).

[Illustration:

FIG. 5.—Diagram to explain the Action of the Motor and Sensory Nerves. ]

There is still, however, a second group of nerves, the _nerves of sensation_ (sensory nerves), which arise in the sense-organs (skin, mucous membrane of tongue, nose, ear, eye), and convey to the central nervous system the impressions they receive from the outer world by the aid of these sense-organs. In the appended diagram (Fig. 5), _C_ represents the central nervous system; _B.N._, a motor nerve, branching in the muscle _M_; _G.N._, a sensory nerve, which runs from the blood-bathed inner skin or dermis (_L.h._), underlying the outer skin or epidermis (_O.h._), to the central system. (The arrows indicate the direction in which impulses are conveyed along the corresponding nerve.)

Men or animals lose in weight if they take no food. The reason for this is that certain substances leave the body either as gases (through the lungs), or as liquids (by the kidneys and sweat-glands), without a corresponding compensation. An animal or human being could not live without taking in fresh substances, which, according as they are solid or liquid, are known as food or drink. The different kinds of food and drink, which, with few exceptions (salts, water), are taken from the animal and plant kingdoms, cannot, however, _as such_, replace the gradually diminishing body substance, for, to begin with, they contain useless matters, which pass out of the body in the _fæces_ (dung). And even the nutritious parts of the animal and vegetable substances taken into the stomach, are not always in a form in which they can be used _at once_. Digestion, which in all the higher animals takes place in a _food-tube_ (gut), serves to reduce them to a suitable condition, at the same time separating the useless matters. The action of several fluids (saliva, gastric juice, bile, etc.) secreted by glands, extracts the useful (nutritious) substances from the food and drink, converting them also into a suitable form. The smaller the pieces into which the food is separated, the better can this purpose be effected. In mammals the teeth serve to break down the food; in birds and many Invertebrates the same part is played by special secretions of the stomach or intestine provided with hard ridges.

So long as the nutritious food-stuffs remain in the food-canal, even though in a completely suitable form, they cannot nourish the body. And since waste of the substance of the body everywhere takes place, it is absolutely necessary that the food-stuffs should pass after digestion into a system of organs going to all parts of the body. This system is the _circulatory_, or _vascular system_. Food-stuffs enter it from the gut directly or indirectly, reaching it in the latter case through the _lymphatic_ (lacteal) system.

The _blood_ is the fluid into which the food-stuffs are taken up. It consists of an almost colourless liquid, together with an innumerable number of exceedingly minute blood-corpuscles.

The blood flows through the body in a system of tubes, or _blood-vessels_, which branch repeatedly, and at last become merged in the microscopic _capillary blood-vessels_. These capillaries are present in nearly all parts of the body except the epidermis and epidermal structures (hairs, feathers, scales, etc.). They have exceedingly thin walls, which present no resistance to the passage of the nutritious substances contained in the blood, so that these can be absorbed by those parts of the body which lie between the individual capillary vessels. The central organ of the circulation is the _heart_, an enlarged part of the vascular system, possessing thick muscular walls. By contraction of these, the blood is driven out of the heart (Fig. 6, _H_); and its exit is possible on one side only (_a_), as at the other side (_b_) there is a valve, which closes when the heart contracts. The vessel into which the blood leaving the heart enters is termed an _artery_ (_S.A._) It divides into several branches, also known as arteries, and the smallest arteries pass into capillaries, which again are connected with _veins_, which join larger and larger veins, until finally one or a few open into the heart (_A_).

[Illustration:

FIG. 6.—Diagram of the Course of the Circulation. ]

Since the blood in the course of its circulation gives up some of its nutriment to the various parts of the body, it would in the end become useless for the purposes of nutrition if it did not receive a fresh supply of food-stuffs from the gut, either directly or indirectly (through the lacteal system). But apart from this, the blood would ultimately become useless, and that very quickly, if it did not traverse the lungs, kidneys, and sweat-glands. It is well known to every one that a man or animal cannot live without air, or at any rate without a certain gas, _oxygen_, that is contained in air. This oxygen must be able to penetrate into the minutest particles of the body, and the blood, in the corpuscles of which it is contained, carries it everywhere. In the smallest particles (molecules) of the body an oxidation (combustion) of body substance takes place, which not only causes an evolution of heat, but also renders the body capable of doing work. But if now the blood passes from the capillaries into the veins, it contains too little oxygen. And besides, it has taken up from the molecules of the body several substances, developed in those molecules, which would be fatal to the animal if they were not removed from the body. Now, when the blood streams through the lungs, it gets rid of the poisonous gaseous matter, and when it traverses the kidneys and sweat-glands it parts with the injurious liquid and solid substances. But in the lungs the blood takes up at the same time fresh oxygen; and since in this way the air in the lungs becomes poor in oxygen, the _movements of breathing_ (respiration) provide for the passage of a fresh supply of oxygen into the lungs. Only the higher Vertebrates breathe by means of lungs; fishes and numerous aquatic Invertebrates breathe by gills, and insects by air-tubes (tracheæ).

[Illustration:

FIG. 7.—The Small-winged Gall-fly, _d_ (_Andricus terminalis_), lays its eggs separately in the rootlets of oak. Root-galls (_a_) result from this, and inside of each of them a larva develops which, after a metamorphosis, becomes a relatively large, wingless gall-fly (_c_) known as _Biorhiza aptera_. This pierces the oak-buds in early spring, and lays a large number of eggs in them; from part of the bud is formed a large juicy gall (_b_), containing several larvæ, from which the small-winged gall flies (_d_) develop. The species here represented exist, therefore, in two forms, _e_ and _d_ (Heterogeny). ]

While _Nutrition_ is the life-process which shields the _individual_ from death, Reproduction serves to maintain the _species_. It is familiarly known that the offspring generally resemble their parents. But it is also a fact recognized by the stock-breeder, that a particular animal will not only transmit several of its _own_ characteristics to its offspring, but perhaps also various characteristics of the grandparents or of animals belonging to still more remote generations, although these characteristics are not visible in the animal which is actually breeding (_Reversion_, _Atavism_). Among insects and the lower animals there are species which, as adult animals, appear not in _one_ form, but two or several. In this case, as a regular thing, the offspring does not resemble the parents, but the grandparents, great-grandparents, or a still earlier generation. The older observers have placed the offspring and the parents, and sometimes the grandparents too, of the same animal species in different species, or even genera or families, until newer researches on the reproduction and development of these animals have proved them to belong to one and the same species (see Fig. 7 and explanation). The method of reproduction by which a species appears in two or several forms is distinguished as _heterogeny_ and _metagenesis_, or _alternation of generations_. In the first (Fig. 7) sexually reproducing animals alternate with other sexual animals. It may be that these are of separate sexes, or else they may possess both male and female organs (_hermaphrodite_). In metagenesis a sexual generation regularly alternates with one or several generations reproducing asexually.

The animal kingdom falls (cf. p. 2) into sub-kingdoms or main divisions. Seven of these are commonly distinguished: I. Backboned animals; II. Jointed-limbed animals; III. Worms; IV. Molluscs; V. Echinoderms; VI. Cœlenterates; VII. Protozoa.

First Sub-Kingdom: VERTEBRATA (BACKBONED ANIMALS).

The Vertebrate body possesses a bilateral or twosided symmetry; _i.e._ it can be separated into two exactly corresponding halves, by a plane of division. The bilateral symmetry is strictly carried out as regards the external parts of the body, a single exception to this being flat-fish (plaice, flounder, etc.); but, on the other hand, it is more or less obliterated in the arrangement of the internal organs. In the Vertebrate body we find, as an axis, a vertebral column (backbone) made up of vertebræ, and traversed by the vertebral canal. As soon as this canal widens out in the skull to the cranial cavity, the spinal cord, which it contains, merges into the brain. In addition to the cavity containing the central nervous system, and placed on the upper side (= dorsal side) of the animal, a cavity, the _body-cavity_, is found in the under side (= ventral side). It contains for the most part the organs of respiration, circulation, digestion, and excretion (Fig. 1), and in Mammals is divided by the diaphragm into _thoracic_ and _abdominal cavities_. In all the other subdivisions of the animal kingdom the central nervous system is situated in the same cavity as the above-mentioned organs.

Various bones are connected with the vertebral column, and they serve for the attachment of muscles. The bones collectively constitute the skeleton, which is one of the most distinctive features of a Vertebrate.

The animals of this sub-kingdom never have more than four limbs, and their blood is red, while that of most other animal groups is colourless.

The structure of the heart in the various Vertebrates must also be noticed. In no Vertebrate is this organ so simple in structure as in the scheme given in Fig. 6; such an arrangement, moreover, would involve great difficulties. One great difficulty would be that while the blood was leaving the heart at _a_ (Fig. 6), no fresh blood could enter, so that the blood in the veins would stand still. Even in the lowest Vertebrates (the Fishes) this difficulty is obviated, for where the main vein (or veins) opens into the heart an enlargement of this vein is found, where the blood can collect as long as the heart continues to contract. This expansion is also reckoned as part of the heart, and named the _auricle_ (Fig. 8, _V.K._), while the heart proper is termed the _ventricle_ (_K._). It is also easy to see that there must be a tolerably wide opening between the two chambers, so that as soon as the ventricle becomes flaccid the auricle can force blood into it. But there being such a wide aperture between auricle and ventricle, one valve is not enough to make it impossible for the blood to pass back into the auricle during the contraction of the ventricular walls. There are two or three valves there (Fig. 8, _Kl._) fixed by fibres to the wall of the ventricle. In order that the blood which is forced into the artery (_S.A._) may not pass into the ventricle during its relaxation, there is another valve (not indicated in Fig. 8), at the base of the artery.

[Illustration:

FIG. 8.—Diagram of the Heart in a Fish. ]

An arrangement like that so far described is found in fishes. The heart consists in them of an auricle, into which is returned the blood that has traversed the body, and of a ventricle which moves it on again. But the blood that has traversed the body is on that account poor in oxygen, and consequently unfit to be circulated again when it is returned to the heart. It is necessary for it to take up fresh oxygen before being circulated again. In fishes this difficulty is met by the blood, poor in oxygen, which flows out of the ventricle, first going to the _gills_ and streaming through them. The gills consist of a very large number of small, thin-walled outgrowths arranged in regular rows on the firm gill-arches. The blood, poor in oxygen, passing out of the ventricle and through various arterial branches to the gill-filaments, takes up fresh oxygen as it streams through these from the oxygen dissolved in the water which constantly surrounds them. For this purpose a stream of pure water is regularly taken in by the mouth and expelled again, right and left, through the gill-slits. The blood, having become rich in oxygen in the gills, is now once more fit for circulation through the body, and therefore flows out of the gill-capillaries into larger vessels, which finally unite into a single large vessel that carries the purified blood to the various parts of the body. In the arrangement of the heart here described there is the disadvantageous condition that the blood is obliged to traverse two sets of capillaries (gill and body capillaries). This is not an easy matter, for there is a great deal of friction between the blood and the walls of the capillaries, constituting a hindrance to its progress. The circulation of the blood in fishes is consequently very slow, and since the blood contains the oxygen which is used by the various parts of the body, oxidation goes on slowly in the body of a fish; hence the small amount of heat developed there. Since fishes almost immediately give off to their surroundings the small amount of heat which they develop, they have no constant body temperature, varying in this respect with the temperature of the surrounding water. Such animals are termed _cold-blooded_.

In all other Vertebrates a more rapid movement of the blood is rendered possible by the insertion of a second heart, quite similar in every respect to the other heart, in the course of the blood between the respiratory organs and the body. The first heart drives the blood through the lung capillaries, and therefore corresponds to the fish-heart; from these capillaries the blood returns to the auricle of the second heart, and from the ventricle of that heart travels to the various parts of the body. When it has completed this course, it returns to the auricle of the first heart. Although these two structures work independently, they lie close together and make up a single organ. We do not therefore speak of two individual hearts, but of one heart with two halves. The first half, which receives the blood, poor in oxygen, that is returned from the body, and sends it on to the lungs, lies on the right, and is termed the _right_ half. The second half, which receives the richly oxygenated blood from the lungs, and pumps it to the various parts of the body, is termed the _left_ half (Fig. 9 and explanation).

In the arrangement just described, which is found in Mammals and Birds, the blood returning from the lungs is propelled with new force through the body, and therefore circulates very quickly, so that the various parts receive a relatively large amount of oxygen in a short time. It is therefore intelligible that Birds and Mammals develop more warmth than Fish. They possess a special, constant body temperature, somewhat different in different species, but usually lying between 98° and 104° Fhr., and they are called _warm-blooded_ animals.

[Illustration:

FIG. 9.—Diagram of the Mammalian Heart. 1, right, 2, left ventricle; 3, right, 4, left auricle; 5, superior, 6, inferior vena cava; 7, pulmonary artery forking into branches for right and left lungs; 8, the four pulmonary veins; 9, the great body-artery (aorta); the arrows indicate the direction of the blood-stream. ]

[Illustration:

FIG. 10.—Diagram of the Heart of a Reptile. Between the right (_r.K._) and left (_l.K._) ventricles is a perforated partition. _r.V.K._, right auricle; _l.V.K._, left auricle; _H.v._, vena cava, carrying back the blood which has traversed the body into the right auricle; _L.art._, pulmonary artery; _L.v._, pulmonary vein; _Ao._, aorta. ]

In Reptiles (snakes, lizards, etc.), the two halves of the heart are not entirely distinct, since there is an opening in the partition-wall between the two ventricles. As a consequence of this, the poorly oxygenated blood of the right half of the heart mixes with the richly oxygenated blood of the left half, the extent to which this mixing takes place being proportional to the size of the aperture. In Reptiles, therefore, the blood supplied to the lungs is not so poor in oxygen as it might be, nor, on the other hand, is the blood supplied to the other parts of the body completely oxygenated. As consequences of this: (1) respiration is feebler, and (2) the development of heat less than in Mammals and Birds (_i.e._ reptiles are cold-blooded), and (3) the chemical changes taking place in the body (the metabolism) go on more slowly than in warm-blooded animals, and we can understand why reptiles execute fewer movements in a given space of time.

[Illustration:

FIG. 11.—Diagram of a Frog’s Heart. (The ventricle _K._ is quite undivided: compare Figs. 9 and 10.) Other letters as in Fig. 10. ]

In Amphibians (_e.g._ frog) the two ventricles are similarly connected, but the opening is still larger than in Reptiles, and the partition-wall may even be altogether absent. It follows, therefore, that the mixing of the two kinds of blood is still more complete, and that Amphibians, too, are cold-blooded.

The vertebrate sub-kingdom embraces the classes of I. Mammals; II. Birds; III. Reptiles; IV. Amphibians; V. Fishes.

Class I.: =Mammalia= (Sucklers).

Warm-blooded Vertebrates (p. 16), usually covered with hair, and bringing forth living young, that suck for some time after birth. The female is provided with milk-glands on the thorax or abdomen, or both those regions.

Speaking quite broadly, the skeleton is like that of man, described on pp. 4–8. There are, however, great differences in detail. The cranium is relatively much smaller, and the bones of the face (especially of the jaws) are usually much larger than in the human skull. The number of the cervical vertebræ is seven in all Mammals, as in man; but the other kinds of vertebræ vary in number in the different species. The number of caudal vertebræ, for example, is very variable. As most Mammals go on all fours, their fore and hind limbs are much more similar than is the case in man. In many the thigh and upper-arm bones are drawn closely up to the body (horse, ox, pig). Mammals never have more than five fingers or toes, but may have fewer. The thumb or great toe is the first to disappear (hind foot of dog, fore and hind foot of pig). There may be only three (rhinoceros), two (ox, sheep), or one (horse) digit developed. In addition to fully developed digits, there are in many Mammals very small stunted ones (“dew-claws” of the stag).

[Illustration:

FIG. 12.—Vertical Section of a Human Grinding Tooth. ]

[Illustration:

FIG. 13.—Crown of a Grinder of the Ox. _a_, cement; _b_, enamel; _c_, dentine; _d_, enamel; _e_, cement. ]

There are also great differences in the way of resting the feet on the ground. Man and bear tread on the soles of the feet (plantigrade); dog and cat walk on the under side of the toes (digitigrade), not on the other parts of the feet. Ox, pig, horse, etc., rest while walking only on the tips of the toes, which are sheathed in hoofs (unguligrade).

The teeth of mammals are wedged into special sockets in the jaw-bones. The structure of a mammalian tooth is made clear by Fig. 12. We first distinguish a pulp-cavity (_p_), which in the living animal is filled with a substance supplied by a bloodvessel and nerve. This cavity is surrounded by the dentine (_d_), a hard substance which makes up the greater part of the tooth. Hard enamel (_s_) covers the whole of the crown in man and many animals, while in certain other forms it is found only on part of the crown. The root of the tooth is covered with cement (_z_), a bone-like substance.

All teeth in which the entire surface of the crown is covered by enamel only are known as _simple teeth_, while those into which the enamel only penetrates in more or less deep folds, leaving the rest of the crown uncovered, are known as _compound teeth_ (Fig. 13). The structure of the teeth is related to the nature of the food. We distinguish three kinds of teeth in the same animal, which, however, are not all present in every species; these are the _incisors_, _canines_, and _grinders_. The first two kinds are changed; but only the anterior grinders, known as the _premolars_, are changed, while the hinder ones, the _true molars_, do not first appear as “milk” teeth, but rather later on with the other “permanent” teeth.

The following orders of Mammals are distinguished: I. Bimana (Man), II. Quadrumana (Apes), III. Carnivora (Beasts of prey), IV. Insectivora (Insect-eaters), V. Cheiroptera (Bats), VI. Rodentia (Gnawers), VII. Ruminantia, VIII. Solidungula, IX. Pachydermata, X. Cetacea, XI. Edentata, XII. Marsupialia (Pouched animals), XIII. Monotremata.

I shall deal here only with those orders which are of agricultural importance.

ORDER: =Carnivora= (BEASTS OF PREY).

In each jaw there are six relatively small incisor teeth; and, on each side of these, a large projecting canine, by which the flesh is torn from the body of the prey (Fig. 14). The premolars and the first of the true molars (the carnassials[2]) are strongly compressed, and have a cutting crown; their outer surface is completely covered with hard enamel. As the lower jaw is smaller than the upper jaw, and is only able to move up and down, not from side to side, the sharp crowns of the premolars, and especially those of the large carnassials, cut along one another, and divide anything coming between them as if with shears. The small molars which are usually found behind the carnassials have broad tuberculated crowns. The temporal (_i.e._ chewing) muscles are strongly developed, the general result of which is that the head is broad. The claws are very sharp in some of the families. The Carnivora are powerful animals, move very quickly, and are endowed with keen smell and sight.

Footnote 2:

The upper carnassials = last premolars. The lower „ = first molars.—TR.

The wild Carnivora living in Britain belong to the families of cats, dogs, and weasels.

Family: =Felidæ= (_Cat Family_).

Typical Carnivora with very large canines and carnassials, two premolars in each half of each jaw, one of the upper molars, but none of the lower ones, small and tuberculated. Tongue rough. Fore and hind feet five-toed. When not in use, the claws are drawn back (retracted). The Felidæ are digitigrade. Backbone very flexible, and with free power of movement. The Felidæ are bloodthirsty, nocturnal animals, many of which climb well, and spring upon their prey.

The group is specially exemplified by the =Domestic Cat=, the parent stock of which is the Nubian cat (_Felis maniculata_), a native of Nubia and the Soudan. The =Wild Cat= (_Felis catus_) is larger than the common kind, and has a thicker tail. Formerly it was tolerably common in Britain, but now only occurs in a few thinly populated districts.

[Illustration:

FIG. 14.—Skull of Domestic Cat. ]

The =Lynx= (_Felis Lynx_), found at one time in Germany, still lives in the Carpathians, and in Switzerland, but occurs more commonly in Scandinavia, Denmark, and Russia.

Family: =Canidæ= (_Dog Family_).

Head longer than in cats; canines and carnassials relatively less developed. Two tuberculated molars on each side of each jaw. Claws not so sharp as those of cats, and cannot be drawn back (_i.e._ are nonretractile). Fore-foot five, hind-foot four toes. Tongue smooth.

The various races of the =Domestic Dog= belong here.

The wolf (_Canis lupus_) is no longer an inhabitant of Britain or Germany, but sometimes crosses the German frontier from Russia, Galicia, Hungary, the Alps, and the Ardennes, especially in winter, and preys upon the larger domestic animals.

The remaining example is—

=The Fox= (_Canis vulpes_).

This animal lives in an underground dwelling, which is either dug out by itself or else is a deserted badger-burrow. It kills roes, fawns, hares, and game-birds; in farms it preys on poultry and eggs. It never commits depredations in the neighbourhood of its burrow, for fear of betraying its hiding-place. Valuable services, however, must be balanced against the damage mentioned above, for it catches many rabbits, and also an enormous number of field-voles in the years when these become a pest. It also often eats insects (_e.g._ cockchafers), worms, and snails. In fact, the fox is perhaps generally of more use than otherwise to the farmer and forester.

Family: =Mustelidæ= (_Weasel Family_).

Elongated, slender; legs short; head small and flat; cranium elongated; tongue smooth. Five toes on each foot, with small, sharp claws. A tuberculated molar on each side in the upper and lower jaws. The weasels give out an offensive odour from stink-glands situated near the anus.

There belong to this family—

1. The =Pine Marten= (_Mustela martes_). Body up to twenty inches, tail up to ten inches long; fur brown, with yellowish wool-hairs; a yellow patch on the throat. Is found in thick woods, where it destroys small birds and squirrels; it also kills much poultry and game.

2. The =Beech=, or =Stone Marten= (_Mustela foina_). About as large as the preceding species; greyish-brown fur, with whitish wool-hairs; a white patch in the throat; chiefly occurs in the immediate neighbourhood of human dwellings, in barns, wood-stacks, etc.; kills a great deal of poultry, sometimes also wild birds, mice, and game.

3. The =Polecat= (_Putorius fœtidus_). Shining brownish black, with yellow wool-hairs; somewhat smaller than the stone marten; in particular, the tail is shorter and its hair is not so long as in the two preceding species. In the summer it lives in the open country, in hollow trees, or in the burrows of foxes and rabbits; in winter it settles down near human dwellings, where it lives in wood and under heaps of brushwood, haylofts, etc. In summer it may do more good by destroying numerous field-voles, water-rats, etc., than harm by devouring those singing birds which are favourable to agriculture; but in winter its undesirable visits to the fowl-house and dove-cot effect much injury. It kills the birds and devours the eggs, sucking without smashing them. In winter, too, it is very harmful to beehives, being fond of honey.

[Illustration:

FIG. 15.—The Pine Marten (_Mustela martes_). ]

The =Ferret= (_Putorius furo_) is undoubtedly a short-legged variety of the common polecat, usually white in colour, and, when that is the case, red-eyed.

4. The =Stoat=, or =Ermine= (_Putorius erminea_). Body twelve inches, tail about three and a half inches long; slender; the body is scarcely broader than the head; tail longer than in the next species; summer fur, cinnamon brown above, white below; tail, cinnamon brown with black tip; winter fur quite white, but the end of the tail remains black. Mostly in fields, in the neighbourhood of plantations or woods; always abundant among sandhills, owing to the rabbits living there. The stoat usually follows its prey at night, stealing upon mice, rats, rabbits, hares, and song-birds; it is also sometimes very destructive in dove-cots and hen-houses. It must, however, be stated that the stoat is on the whole more useful than harmful.

5. The =Weasel= (_Putorius vulgaris_). Smaller than the stoat; head larger and thicker than the extremely slender, almost snake-like, trunk; legs short. The weasel is a very sharp little animal, and can easily pass along mouse-holes. Summer and winter coats alike—back brown, belly white. Its food chiefly consists of field-voles, also of rats and water-rats, young hares and rabbits, birds building near the ground, and also their eggs, which the weasel, by holding under its chin, manages to carry to its home; occasionally also lizards, blindworms, snakes, and frogs. The weasel does some damage in fowl-houses and dove-cots, and is also destructive to game. This, however, does not outweigh its very great use, since it is above all an untiring vole-catcher. When in any region the field-voles have multiplied excessively, an immigration of weasels takes place from surrounding parts. In years when there is a plague of voles the usual breeding time in spring is followed by another later on. A very large number of weasels may be found in a vole-infected district, and they thin out the mischievous rodents in a surprising manner. Nor are the weasels less useful in summer than in winter. They even follow under the snow the voles which winter in the country, and the slaughter effected at this period must exert a great influence on the following season, when these animals recommence their injurious work, and a pair of them that have survived the winter may perhaps produce two hundred others before the end of the summer.

6. The =Mink= (_Putorius lutreola_) is as large as a polecat, and may be regarded as a sort of link between it and the others. Leg and ears short; skin smooth-haired, brown both on the back and the belly; chin, lips, and a small patch on the neck, white; tail about one-third the length of the body. In well-watered regions on the banks of rivers, lakes, and ponds. Eats water-rats, water-birds, frogs, salamanders, fish, crayfish, water-insects, water-snails, and aquatic bivalves. Holstein, Mecklenburg, Pomerania, Brandenburg, Silesia.

7. The =Otter= (_Lutra vulgaris_). Body flattened; legs short, with webbed toes; snout rounded; ears short, and can be closed by a fold of skin; tail flat, and pointed at its tip. Length of the body, twenty-eight to thirty-two inches; of the tail, fourteen to sixteen inches. Skin smooth-haired, shining dark brown above and below. Found on the banks of lakes, pools, ponds, rivers, brooks, etc., where fish is plentiful. It catches water-rats, ducks and geese, as well as their young, wild water-birds, frogs, fish, crayfish, water-insects. Especially destructive to fish.

8. The =Badger= (_Meles taxus_). Body heavy; legs short, plantigrade; toes with strong digging claws; snout pointed; canines not very large; both they and the carnassials much worn in old animals. Tuberculated molars well developed. The dentition and whole structure of the body show that the badger is not exclusively a flesh-eater. Length of body, three feet; weight, 22 to 33 lbs. Fur tolerably long-haired, yellowish whitey grey, mixed with black. Head with longitudinal stripes of black and white; tail short, yellowish grey.

The burrow is very large; several passages, the openings of which may be ninety-seven feet apart, lead to the exterior. The badger only leaves its dwelling in the evening. It eats mice, birds which nest on the ground, especially their eggs and young, snakes, frogs, cockchafer grubs, earthworms, insects; also turnips, carrots, acorns, and sweet fruits. Although it is both harmful and useful, the latter is more generally the case. Its digging habits, however, are sometimes destructive, since it throws up young trees and other plants by the roots. The badger often sleeps several days in succession during the winter, although it does not hibernate. Its fat is used up during the winter.

ORDER: =Insectivora= (INSECT-EATING MAMMALS).

Since the Insectivora feed upon very small animals (insects, worms, snails), they cannot themselves be large. Only those species (hedgehog) which feed on small mammals and birds or upon vegetable matter, in addition to insects, are of medium size. The native species all live on or in the ground. The snout is extremely slender, and does duty as an organ of touch. The eyes are usually very badly developed. Incisors sharp; and the back teeth, which are completely coated with enamel, are remarkable for their pointed crowns. When the mouth is closed the upper teeth fit into the spaces between the lower teeth, and _vice versâ_. Consequently the shutting of the mouth forces the points of all the back teeth into any insect which happens to be between the jaws. The Insectivora are plantigrade (p. 22). Here belong the following forms: the Shrews (_Sorex_), the Mole (_Talpa europæa_) and the Hedgehog (_Erinaceus europæus_).

[Illustration:

FIG. 16.—Skull of the Mole. ]

The =Shrews= (_Sorex_) are small animals with a superficial resemblance to mice, with slender soft-haired bodies, small eyes, and tolerably long, thickly haired tails. Shrews are extremely voracious, eating daily more than their own weight of food, and destroying an enormous quantity of subterranean vermin. They live in underground passages, not usually made by themselves, but dug out by field-voles. They smell strongly of musk, secreted by two glands in the hinder part of the body.

The blackish brown Shrew-mouse, or =Common Shrew= (_Sorex vulgaris_), and the =Lesser Shrew= (_Sorex pygmœus_), only about two inches long, kill, in the cornfields, gardens, or woodland, an enormous quantity of noxious insects found in the earth, together with their larvæ; also snails and worms, and sometimes field-voles, and are in the highest degree serviceable. But the larger (up to 3½ inches long), black =Water Shrew= (_Sorex fodiens_), although serviceable on land in the same way as the other kinds, is very injurious to fishing and fish-breeding, since it devours the small fish and kills the larger ones, eating out their eyes and brains.

[Illustration:

FIG. 17.—The Common Shrew (_Sorex vulgaris_). ]

The =Mole= (_Talpa europœa_). Body thick, cylindrical. Legs short, fore legs broad and spade-like, with broad digging claws. Eyes small, scarcely visible among the fur. No external ears; the auditory opening can be completely closed by a fold of skin. Shining black fur. The mole is found in every soil inhabited by insects and earthworms, provided it is not too stiff, but yet sufficiently coherent to dig passages in, which will not at once collapse. Its presence is known by the heaps which it throws up. The nest, however, is always found under a larger heap, frequently hidden under tree roots, walls, etc., though sometimes in the open field. It consists in the first place of a nearly round dwelling-chamber, softly upholstered with vegetable substances; this is surrounded by a labyrinth of passages. From the nest a passage runs to the mole’s hunting-ground. The walls of this passage of the labyrinth, and of the nest, are hard. The wider and subterranean channels, which the mole digs out when it is simply catching insects in the soil, easily fall in again, and the animal takes no pains to compact their walls. The highway to the hunting-ground, in which the animal can progress very rapidly, can be at once detected, not like the ordinary passages by a small chain of mole-hills composed of the thrown-up earth, but by a depression, since in its preparation the earth is laterally compressed and not thrown out. This tube is shorter or longer according as the hunting-ground is in the immediate neighbourhood or further off; it may be 100 or 160 feet long. The mole sleeps in the nest during the time not employed in seeking for food, and goes three times a day on the hunt for insects (early morning, midday, and before sunset in the evening). Having reached the subterranean hunting-ground, it tracks to some distance the insect larvæ, and worms found in the soil, being aided in this by its long snout. It daily devours more than its own weight. During summer the mole digs its passages near the surface, since larvæ and worms are then found in the uppermost layer of earth. In winter, when these withdraw into the depths of the soil, it digs much deeper channels. It does not fall into a winter-sleep. The young (three to seven) are born in May, June, or July. The mole never gnaws plants. It does service, sometimes very great, by eating many wireworms, grubs, snail embryos, earth caterpillars, mole-crickets, and other earth-inhabiting insects, as well as their larvæ. It also willingly eats earthworms, but whether this does good is not definitely known. But under certain conditions it may also do harm, rooting up plants as it makes its heaps. Grass and grain suffer little, if at all, by this; other plants more; while young flax-plants perish if their roots are loosened. Mole-hills in hayfields and cornfields are a nuisance at harvest time. Moles are not to be endured in the neighbourhood of dams, since their borings may become the immediate cause of flooding. Trapping may usefully be resorted to in cases where moles are harmful.

The =Hedgehog=, or =Hedgepig= (_Erinaceus europæus_). When danger threatens it rolls itself into a ball covered all over with prickles, and is in this way secured from the attacks of most enemies. The hedgehog goes on the hunt in the evening; while during the day it sleeps in its hiding-place, situated in such places as the side of a ditch, hedges, or under heaps of brushwood. It preys more particularly on field-voles, sometimes also on eggs and small birds (chickens occasionally), lizards, grass-snakes, adders (by the bites of which it is unaffected), frogs, cockchafers and their larvæ, field snails, earthworms, and similar small deer; now and then on fallen fruit and juicy plant roots.

ORDER: =Cheiroptera= (BATS).

[Illustration:

FIG. 18.—Skeleton of a Bat. ]

All Bats, except a few tropical genera, feed on insects, and possess teeth like those of the preceding order of Mammals (p. 30). The leading feature is the characteristic modification of the fore limbs into a flying apparatus. The bones of the fore arm (Fig. 18, _u, r_), the metacarpels (_mc_), and the phalanges (except in the case of the thumb, which possesses a sharp claw (_p_)) are of great length; and between the long fingers, between the fore and hind limbs, and, last of all, between the two hind limbs there is an elastic membrane, serving both for flight and touch. Sight ill developed, since the bat is a nocturnal animal; a delicate sense of touch has its seat not only in the flying-membrane, but also in the skin of the ears, which are often very large, and in the membranous flaps which, in a few genera (the “leaf-nosed” bats), occur on the nose and lips. As is well known, bats sleep in the day; and they also hibernate in chimneys, hollow trees, ruins, and other similar places of concealment.

They principally devour night-flying moths, and spiders; and, since they use a great quantity of nourishment, are of great service, since the caterpillars of many of the species they destroy are very injurious to agriculture or forestry. About nine species live in Britain, but there is no use in enumerating them here.

ORDER: =Rodentia= (GNAWING MAMMALS).

[Illustration:

FIG. 19.—Skull of Squirrel. ]

Two long incisors (Fig. 19), the crowns of which are continually being worn down, while a corresponding growth takes place at the root-end. These incisors are used for gnawing, in which process the lower jaw is rapidly moved backwards and forwards. Gnawing wears down these teeth less in front than behind, owing to the presence of a thick layer of enamel in the former position. Their crowns, therefore, maintain a chisel-edge. That the incisors never stop growing is clearly seen when the usual wearing down does not take place, as, _e.g._, when the lower jaw is placed obliquely under the upper jaw, or when a tooth is absent in one jaw, under which circumstances the corresponding incisor in the other jaw is not worn down. In such a case the incisors continue to grow, ultimately curving upwards or downwards, and becoming tusk-like structures (Fig. 20). The Rodents have no canines. In those Rodents which feed both on animal and vegetable food (the “Omnivora,” _e.g._ squirrel, common mouse, brown rat, etc.), the crowns of the back teeth are completely covered with enamel; in the purely vegetable feeders (“Herbivora,” _e.g._ hare, rabbit), they are compound teeth (p. 22). In most Rodents the hind feet are longer than the fore, giving a springing gait. Eyes large. Many forms have “cheek-pouches,” in which the food they obtain can be stored up for some time. When the pouches are full, a muscle contracts by which their ends are drawn backwards; they are emptied by the animal pressing them with its fore feet. The majority of Rodents are small, they are at most of medium size (hare). The majority of the species have great powers of reproduction, by which the injurious kinds are sometimes rendered a very great pest. The British forms injurious to agriculture principally belong to the families of hares, mice, and voles. The squirrel (_Sciurus vulgaris_), and the dormice (especially _Myoxus avellanarius_) are solely of importance in forestry.

Family: =Leporidæ= (_Hares and Rabbits_).

Skull somewhat long. Two small incisors behind the two large upper ones. Ears long and spoon-shaped. Upper lip cleft. Back teeth with enamel folds. Here belong the hare (_Lepus timidus_) and rabbit (_Lepus cuniculus_).

=Hare= (_Lepus timidus_). Ears longer than the head. Eyes yellowish brown. Fur rusty yellow to grey on the upper side, white on the under side. The doe litters in an open “form;” the young are born covered with hair and with open eyes. Mature animals breed four or even five times a year, producing two to four leverets each time. The hare is injurious to agriculture, eating cabbages, rape, turnips, clover, vetches, young corn plants, carrots, and grass. It also eats many weeds. It is, however, less injurious than the rabbit, for it does not burrow. The damage done by the hare is also less evident, since this restless, fastidious animal seldom feeds continuously in the same spot.

[Illustration:

FIG. 20.—Abnormal Tooth in Hare. ]

=Rabbit= (_Lepus cuniculus_). Ears shorter than the head. Eyes dark brown. Fur yellowish brown to greyish yellow on the upper side, redder in front. Under fur bluish grey. Shape more compressed. The rabbit breeds more rapidly than the hare. Five to six times yearly the doe brings forth four to eight young, which, after six months, can again reproduce. Dwelling subterranean. Young, blind and hairless at birth. As the rabbit burrows, it is limited to certain districts, for the soil must not be too stiff and firm, nor, on the other hand, too light and incoherent. The rabbit is injurious in the same way as the hare, but the damage is more obvious (see above); and as a result of its burrowing habits it does infinitely more damage. Both in sandhills and in alluvial sandy soil rabbit burrows lead to the blowing away of material only held together by sand-plants. Kept down by shooting, netting, and ferreting (p. 27).

Family: =Muridæ= (_Mouse Family_).

The mouse-like animals (the larger species of the family are called “rats”) closely resemble the representatives of the following family, but are distinguished from these (the “voles”) by their slender body, longer legs, a more pointed head with longer always clearly visible ears, and usually, with the exception of the hamster, by a tail equal in length to the body. The hind legs are longer than the fore legs, hence the hopping mode of progression. Three back teeth on each side of each jaw, possessing a tuberculated crown completely covered with enamel.

[Illustration:

FIG. 21.—The Hamster (_Cricetus frumentarius_). ]

The =Hamster= (_Cricetus frumentarius_).—The Hamster has cheek-pouches, and a very short, thick, but short-haired tail. It attains the size of the brown rat. Bright yellowish brown; belly and legs black. The hamster is found almost exclusively on fertile soil devoted to cultivation. It appears locally, and then for several years in great abundance, so that it is often caught in tens or even hundreds of thousands. Favourite food: wheat, field beans, and peas, then rye and similar grain; and, last, roots, turnips, young corn plants. Sometimes, too, the hamster eats animal food—worms, insects, lizards, small birds, eggs, and mice. As a winter store it usually only accumulates grain, beans, and peas in its hiding-place, often to the amount of more than five gallons. A little heap of thrown-out soil marks on the surface the position of its nest. The entry to this runs vertically down into the soil. Six to twelve young, twice a year. The dwellings of the hamster, which are situated in stubble-fields, can easily be found; and by digging them up, particularly in spring and late summer, when there are young ones, the number of these destructive Rodents can be greatly reduced. May be caught in traps.

=Genus Mus= (Mice and Rats) includes Rodents without cheek-pouches, and with long, scaly, ringed tails. Two large species (“rats”) belong here, namely—

The common =Black Rat= (_M. rattus_), indigenous to Europe since pre-historic times, and the stronger, somewhat larger—

=Brown Rat= (_M. decumanus_), with greyish white belly (while the first-named species is black on the upper and only slightly brighter on the under side). The brown rat migrated during the first half of the eighteenth century from Asia into Russia, and about the same time from Further India to England by means of ships. Since then it has spread all over Europe and other parts of the world, and in many regions has quite driven out the black rat. Both kinds of rat eat almost everything, and are a pest in housekeeping, as well as in agriculture. They feed on insects, mice, eggs, and chickens, will even bite pieces from the living bodies of grown poultry and fattening swine, and also devour young geese and ducks. They eat grain, peas, beans, potatoes, carrots, turnips; bread, cheese, and similar provisions. Multiply very rapidly. Can be driven away by clacking-mills, and to a great extent by noise. Caught in traps.

Besides these, four mice belong here:—

The =Common Mouse= (_Mus musculus_). Back yellowish grey-black, gradually shading into a somewhat lighter tint on the under side.

[Illustration:

FIG. 22.—The Long-tailed Field Mouse (_Mus sylvaticus_). ]

The =Wood Mouse=, or =Long-tailed Field Mouse= (_M. sylvaticus_). Back a brown shade of yellowish grey; belly white, sharply marked off; relatively very long hind legs, hence a hopping gait. The long-tailed field mouse penetrates tolerably far into woods, but is also found in plantations and gardens, sometimes also in quite treeless regions. On arable land it may adopt the habits of the field vole (p. 42), but as it does not multiply so rapidly is not nearly so injurious. It may also live either for a short time or permanently in houses, adopting the same habits as the common mouse.

The =Harvest Mouse= (_M. minutus_). Small, pretty; back yellowish brown red, belly of a sharply marked-off white. Lives in cornfields during the summer; in harvest time by the field-paths; during winter in barns and haystacks, but also in outdoor nests in the fields. Climbs among the grass and corn-haulms, and the small stems and branches of other plants, including shrubs, holding fast, not only by the feet, but also by the tail. Builds a beautiful spherical nest with a side entrance out of the haulms and leaves of grass and corn, or out of other leaves. Devours seeds, especially grain, oats being the favourite.

The =Corn Mouse= (_M. agrarius_). Back brownish red with longitudinal black stripes. In plains east of the Rhine. Usually local, but then very abundant. Chiefly in cornfields and fruitfields; digs holes in the soil. In autumn it often occurs in the field in large colonies. Food: grain, beans, peas, potatoes, turnips, carrots. In winter in the barns and dwelling-houses of farmers.

[Illustration:

FIG. 23.—Upper Back Teeth of Brown Rat, seen from grinding surface. ]

[Illustration:

FIG. 24.—Upper Back Teeth of Water Vole, seen from grinding surface. ]

Regarding the means of destroying those mice which are sometimes damaging to agriculture (_M. sylvaticus_ and _M. minutus_), see methods mentioned under “Field-vole” (p. 43).

Family: =Arvicolidæ= (_Vole Family_).

The large voles are also popularly called “rats,” the smaller ones “mice.” They closely resemble the true mice and rats (p. 38), but are distinguished from them by their plumper, more compressed body; a thicker head with blunt snout, and ears quite hidden in the fur; and a short, tolerably hairy tail, on which no rings of scales can be distinguished. There are on each side of each jaw three back teeth, of which each appears to consist of two rows of three-sided prisms, fused together along the middle line (cp. Figs. 24 and 23). The native species all belong to the genus _Arvicola_; the Bank Vole (_Arvicola glareolus_), the Water Rat, or Water Vole (_A. amphibius_), and the Short-tailed Field Mouse, or Field Vole (_A. agrestis_).

The brownish-red =Bank Vole= (_A. glareolus_) occurs in forests.

The =Water Rat=, or =Water Vole= (_A. amphibius_). Body six inches long, tail half the length of the body. Fur of one colour, brighter on the under side, varying from brownish grey to brownish black on the back, and from whitish to greyish black on the belly. On the banks of rivers, brooks, ditches, canals, etc.; also on damp low-lying meadows and fields. Digs much-branched passages in the soil; this often takes place in embankments to such an extent that it finally leads to their complete destruction. The vole also does damage in grass-fields and cornfields in the same way as the mole (p. 33). In its case, however, there is no compensating service. It certainly eats insects and worms, but its chief food is of vegetable nature; grain, potatoes, turnips, and carrots are devoured by it in large quantity, and in particular stored up in its hiding-place. It also destroys the roots of grass and corn, and eagerly devours chickens and the eggs of ducks and geese. A variety (_A. amphibius_, var. _terrestris_) occurs in dry soils, and is distinguished by its smaller size, lighter colour, and shorter tail. Its habits are the same as those of the ordinary form, but it is more given to attacking trees.

Traps, shooting, poisoning with celery stumps hollowed out and filled with phosphorus, or else with phosphorus paste.

The =Field Vole=, or =Short-tailed Field Mouse= (_A. agrestis_). A small animal, with dark brownish grey back and greyish white belly. [Lives in pastures, especially those which are low-lying and damp. Large numbers are found together, and they make deep burrows in the soil, each pair having a special nest to themselves. Three, four, or even more litters per year; four to ten young in each litter. Its favourite food consists of roots, young shoots of grass, etc., and the tender bark of shrubs, but nothing of vegetable nature comes amiss. Specially destructive in permanent pasture.]

REMEDIES. (_a_) _Preventive measures_. Protection of its natural enemies (weasel, stoat, polecat, fox, hedgehog, owls, buzzards, kestrels, the smaller seagulls). Catching in traps, etc., in the spring, when the voles are only present in small numbers.

(_b_) _Destructive measures_, which should be as generally used as possible in infested districts. If a field has been completely devastated, or the crop is over: (1) Working the soil with a spiked roller; (2) Partial inundation of the lower-lying fields. If it is desired to kill the voles and spare the crop as well, the following means may be recommended: (1) The digging of cylindrical holes six inches across and two feet deep, especially at the margins of the fields and in the furrows, as well as—at harvest time—on any footpaths that may be found. The voles fall into these holes, cannot get out again, and are starved. (2) The employment of poisons. (Care must be taken that no children or domestic animals are poisoned.) Phosphorus paste is best.

[Illustration:

FIG. 25.—The Southern Field Vole (_Arvicola arvalis_). ]

The =Southern Field Vole= (_A. arvalis_) plays the same destructive part on the Continent that the preceding form does here (Fig. 25). _Remedies_—see above.

ORDER: =Ruminantia= (CUD-CHEWING MAMMALS).

The feet end in two hoof-covered toes, besides which two “after toes” are present. The upper incisors are absent, with few exceptions, but many deer have canines in the upper jaw. The back teeth of Ruminants are compound teeth. The lower jaw is smaller than the upper, and during chewing undergoes lateral movements, so that the plants taken in as food are ground up, as it were, into small pieces, between the projecting enamel ridges of the upper and lower back teeth. The stomach consists of four subdivisions; these are (1) the rumen, or paunch, where the greater part of the food and water taken collects; (2) the reticulum, or honey-comb stomach; (3) the psalterium, or manyplies; (4) the abomasum, reed, or rennet stomach. The last is the second largest part, and in it the same chemical changes take place as in the simple stomach of a non-ruminant. After the food has remained for some time in the paunch it passes up again through the gullet, and [as the “cud”] undergoes a second chewing. The soft mass resulting is once more swallowed, and passes into the psalterium and abomasum.

[Illustration:

FIG. 26.—Skull of a Sheep. ]

Not only the families of _Tylopoda_ (Camels, Llamas), and _Camelopardalidæ_ (Giraffes), but also the large family of _Cavicornia_, to which, amongst others, the ox, sheep, and goat belong, will be passed over in this book. I need only mention the—

Family: =Cervidæ= (_Deer Family_).

Deer have branched horns, known as antlers. With the solitary exception of the reindeer, they are only found in the males. They are bony structures borne upon projecting knobs (horn cores) of the frontal lines. After each rutting-season the antlers are cast, new ones, clothed at first with a soft skin [the “velvet”], are developed. Before the next rutting-season the dermal part of the skin unites firmly with the underlying antler, and becomes itself ossified, while the epidermis shrivels up, partly peels off in bits, and is partly rubbed off by the animal against tree trunks. If the conditions of life (food, weather) are favourable, the animal acquires a new side branch to each antler every year, at any rate, so long as he continues to get bigger and stronger. The one-year-old male (“brocket”) has therefore a simple unbranched antler, the two-year-old (“spayad”) one side branch as well, the three-year-old (“sorel”) three points in all; the four-year-old (“staggard”) has four points; the five-year-old (“stag”) five, and so on.

[Illustration:

FIG. 27.—Development of Roebuck Antlers. ]

In Britain two indigenous deer are found—the Red Deer (_Cervus elaphus_) and the Roebuck (_C. capreolus_); a third species, the Fallow Deer (_C. dama_), lives in South Europe and Asia Minor [and the exact date of its introduction into Britain is not known].

The =Red Deer= (_Cervus elaphus_). Six to seven feet long, and four feet high. Antlers rough and cylindrical for their entire length; each in its normal condition has two front branches [“brow” and “bez-tyne”], a middle branch [“tres”], and a “crown.” Tail small. Body of a brownish colour, becoming red in summer. A light yellowish brown spot on the tail. Male larger than the female, with long dark hairs on the neck during the breeding season (autumn). The young (“calves”) are spotted with white till their first change of coat in October. The hind brings forth one or rarely two calves in May or the beginning of June. The stag sheds his antlers at the end of February; the new ones are already full-grown in July. So long as they are growing the stag keeps to the low woods, and first seeks the high-lying forests when they are completed. He only leaves the forest for any length of time during the breeding season, but, wherever possible, comes to the field for a short time every evening to feed on cabbages, peas, beans, young corn, clover, lupines, grass, etc. Turnips, carrots, and potatoes, dug out of the ground by the fore legs, are also devoured. In this way red deer do a great deal of damage, not only directly in feeding, but also, to a larger extent, by trampling down the crops. In autumn and winter they chiefly feed on acorns, beechnuts, buds and young shoots of various trees. They also peel the bark from young trees, and often cause damage while rubbing the remains of the velvet from their antlers. Red deer are injurious to agriculture and forestry. Suitable fencing of fields, gardens, etc., to be protected.

The =Roebuck= (_Cervus capreolus_) measures up to three and a half feet long, and about two feet high. Antlers (Fig. 27) only slightly branched, and rough all over; beams and branches cylindrical. No brow-tynes, and usually only three branches. Tail extremely small and inconspicuous. Legs long and slender. Summer coat greyish brown, passing over to a reddish tint; the longer winter coat brownish grey. A whitish patch on the rump. The young (“fawns”) have at first white spots on a brownish ground.

Breeding season in August. The female (“doe”) brings forth her two fawns in May or June. The roebuck keeps principally to the lower and middle forests, especially in places where glades, rich in grass and herbage, and cornfields or meadows alternate with woodland. In the evening it comes out of the cover to eat in the fields and meadows; towards morning it withdraws again. The roebuck devours both young corn and corn in the ear; also ears of millet, beans, peas, clover, and lupines. It does not appear to touch potatoes and turnips. The bucks in particular do much mischief by trampling about in cornfields.

The =Fallow Deer= (_Cervus dama_) is about four feet long and three feet high; antlers rough and cylindrical only towards the root, with tolerably smooth, flat, shovel-like ends. Old individuals are pale brown, the summer coat is reddish and brightly spotted; belly whitish; a white patch on the tail. The young have sharply marked bright spots. In its habits this non-indigenous species agrees in many respects with the red deer, but changes its abode less. Towards evening it eagerly leaves the forest in order to seek its food in the cornfields. As the fallow deer lives in large herds its trampling does much damage.

ORDER: =Multungula= or =Pachydermata= (MANY-HOOFED OR THICK-SKINNED MAMMALS).

Non-ruminating hoofed animals with thick, often callous, naked, or scantily haired, frequently bristly skin and with three to five toes, which, though they are not all developed to the same extent, are yet never rudimentary. The various species are very unlike one another as to food and dentition. Here belong domesticated swine, and a single species—formerly occurring wild in Britain—

The =Wild Boar= (_Sus scrofa_). On each foot four toes, of which the two hinder are small and do not usually touch the ground. The wild boar agrees in the general conformation of its body with the common domesticated swine. Six incisors in upper and lower jaw; the lower ones forwardly directed. The canines, which are more developed in boars than sows, curve outwards and upwards in both jaws as “tusks.” On each side of each jaw seven tuberculated back teeth completely covered with enamel. Length of the body 5 feet 10 inches; length of tail 1 foot 8 inches. Colour: black and rusty brown. The young ones are white, spotted and striped with dark brown. The wild boar likes damp, swampy, but at the same time thickly overgrown districts, where it remains hidden in the day, only seeking the fields and meadows when it has become dark and quite still. It then chiefly feeds on turnips, carrots, and potatoes, rooting them out of the ground; it also devours leguminous crops and grain, but treads down far more of these plants than it eats. Besides this, it also feeds on acorns, beechnuts, hazel-nuts, and truffles. The wild boar does some service by devouring snails, worms, insect larvæ living in the soil, and also the pupæ of destructive species of caterpillars, which occur in the same situation; also voles. Thick hedges, in order to protect the corn from injury.

ORDER: Solidungula (SINGLE-HOOFED MAMMALS),

to which the horse and the ass belong, need not be dealt with here; still less the other orders enumerated on p. 23.

Class II.: =Aves= (Birds).

Warm-blooded Vertebrates, which breathe by lungs, are covered with feathers, have no teeth but a horny beak, and lay hard-shelled eggs, which are hatched by the warmth of their body. They are adapted for movement in the air, though not all to the same degree. The fore limbs are modified into wings, in which, however, the parts found in Mammals can be recognized. We distinguish in the first place a small thumb, and then in most cases a two-jointed forefinger and a small second finger. _Secondary quills_ (Fig. 28, BB) are attached to the ulna, and _primary quills_ (A, 1–10) to the two metacarpals and the finger joints, while the thumb bears the bastard wing (C). The tail feathers, or _rectrices_, are attached to the last joint of the tail. The body is clothed with stiff, tolerably long _contour feathers_, which conceal the soft short _down_ from view. The bones are hollow and filled with air. Their cavities are connected with _air-sacs_, which are found in all parts of the body, and fill themselves with air from the lungs when the bird begins to fly. In this way its specific gravity is reduced. The body firm, especially the hinder part of it, which is almost immovable; the neck, which may consist of many vertebræ (even as many as twenty-two), can, on the contrary, be turned in many directions. Birds walk entirely on their toes; the metatarsals are fused with one of the rows of tarsals into a “_tarsus_” bone. Tarsus and toes are covered with horny scales.

A bird’s egg (Fig. 29) consists of a germinal disc (_h_) from which the young bird develops, and which rests on the yolk, made up of substances serving for the nutriment of the developing bird: the yellow (_a_) and the white (_b_) yolk, as well as the albumen (_c_, _c_^1, “white of egg”) in which lie two twisted cords (_chalazæ_),—finally of protective structures: the shell-membrane (_e_) and the calcareous shell (_f_); _g_ is the air-chamber.

[Illustration:

FIG. 28.—Wing of the Buzzard. ]

[Illustration:

FIG. 29.—A Bird’s Egg. ]

When the young escape from the egg, they are either able to at once look after themselves more or less, at least to look for their food,—in which case they can see and are clothed with feathers at hatching (_precocious young_; _e.g._ fowls, ducks, gulls, and pewits),—or the young remain some time in the nest, as they are, to begin with, both blind and naked, and in this case they are fed for some time by the parents (_nestlings_; _e.g._ birds of prey, sparrows, nightingales, pigeons). In the frigid and temperate zones most species of birds do not remain in their native country after the breeding season; those which go south in the autumn are termed _migrants_; while birds which do not migrate, but remain in the district where they have bred, are known as _residents_ (sparrow, jay, magpie). _Gipsy migrants_ execute more or less extensive wanderings, influenced by want of food or other causes (woodpecker, titmouse, golden-crested wren, tree-creeper). The travels of such birds are not, like those of migrants, undertaken at a definite time of year, or in definite directions (N., S.), but many of their species collect together in large flocks for the purpose of wandering, like migrants.

The following orders are usually distinguished:

[Illustration:

FIG. 30.—The Eagle Owl (_Otus maximus_). ]

I. _Raptores_ (Birds of Prey), II. _Scansores_ (Climbers), III. _Passeres_ (Singing Birds), IV. _Gyrantes_ (Doves), V. _Rasores_ (Scratchers), VI. _Grallatores_ (Waders), VII. _Natatores_ (Swimmers), VIII. _Cursores_ (Running Birds).

The Order Cursores includes the ostrich-like birds, and will not here receive further notice.

ORDER: Raptores (BIRDS OF PREY).

Upper beak hooked, covered with a skin (_cere_) at its base; four toes possessing strong claws, and provided with pads in their under side (Fig. 31); wings powerful. Birds of prey live in pairs, and breed once a year in nests composed of pieces of wood and branches. The young are nestlings (p. 51). Sight keen. These birds feed almost exclusively on vertebrates, principally mammals and birds. An idea of their food can be gained by examination of their “pellets”—roundish balls composed of the indigestible parts of their food, and disgorged from twelve to twenty hours after feeding. Two groups are distinguished—_diurnal_ and _nocturnal_ birds of prey. The first (Figs. 31, 32) have a laterally flattened head, eyes directed laterally, and tolerably stiff feathers. The nocturnal forms (“owls,” Figs. 30, 33) have a large head, flattened in front, with large eyes facing to the front, soft plumage, and hair-like feathers on the toes, of which two are directed forwards, one backwards, and one outwards. The radiating feathers round the eye constitute a “veil.”

[Illustration:

FIG. 31.—Head and Foot of Falcon. ]

Predominatingly harmful (from killing domestic mammals) are the following species occurring in Britain: the =Sea Eagle= (_Haliaëtus albicilla_), the =Golden Eagle= (_Aquila chrysaëtus_), the =Peregrine Falcon= (_Falco peregrinus_), the =Merlin= (_F. œsalon_), the =Hobby= (_F. subbuteo_), the =Sparrow Hawk= (_Accipiter nisus_), the =Kite= (_Milvus regalis_), the =Goshawk= (_Astur palumbarius_), the =Harriers= (_Circus cyaneus_ and _C. cinerarius_), and the =Honey Buzzard= (_Pernis apivorus_). The last effects damage by catching honey bees.

[Illustration:

FIG. 32.—The Golden Eagle (_Aquila chrysaëtus_). ]

Useful in the main, being destroyers of field-voles, are the following: the =Kestrel= (_Falco tinnunculus_), the =Buzzard= (_Buteo vulgaris_), the =Barn Owl= (_Strix flammea_, Fig. 33), the =Brown Owl= (_S. aluco_), the =Little Owl= (_Athene noctua_), a casual, the =Short-eared= or =Woodcock Owl= (_Otus brachyotus_), the =Long-eared Owl= (_O. vulgaris_), and the =Eagle Owl= (_Otus maximus_, Fig. 30), a rare visitor.

A bird of prey cannot simply be classed as harmful or useful; a species mainly injurious may sometimes destroy a field vole or a destructive bird, while a useful species may sometimes attack domestic poultry. Game-preserving is destructive of almost all the indigenous diurnal birds of prey, and of the owls to a less extent.

ORDER: Scansores (CLIMBERS).

Birds with two toes directed forwards and two backwards. The young are nestlings. Here belong toucans, parrots, cuckoos, and woodpeckers. The first two groups are limited to the tropics; woodpeckers are only of importance in the culture of fruit trees and in forestry. I describe briefly—

[Illustration:

FIG. 33.—The Barn Owl (_Strix flammea_). ]

The =Cuckoo= (_Cuculus canorus_, Fig. 34). Fourteen inches long, tail eight inches. The yellowish beak is slightly curved; feet yellow. Back blue-grey in old birds, brownish in young ones. Belly white with dark transverse lines. Ten tail quills, flecked with white. Shy; flies like a bird of prey. The female lays her eggs at intervals of about fourteen days, and cannot therefore hatch them out herself. She lays the egg on the ground, and then takes it in her bill to the nest of a small bird which feed its young with insects (wagtail, grasshopper warbler, nightingale, robin, lesser whitethroat, wren, lark). The cuckoo’s egg is generally hatched by the foster parent, and the true young often do not come out from the egg, owing to lack of warmth; or, if hatched, they are thrown out later on by the much larger, rapidly developing young cuckoo. Every cuckoo, therefore, is so far harmful that it costs the lives of several insect-eating birds. But it far more than compensates for this by destroying insects. It is especially beneficial to fruit-tree culture and forestry, since it eats an enormous number of caterpillars; but in late summer it comes frequently from the woodland into the fields, and then eats the caterpillars of the cabbage white, cabbage moth, and silver Y moth, surface caterpillars, and the larvæ of the turnip saw-fly. It also devours mole-crickets and (naturally in the spring) cockchafers.

[Illustration:

FIG. 34.—The Cuckoo (_Cuculus canorus_). ]

ORDER: Passeres (PERCHING BIRDS).

This order is essentially constituted by all those birds with helpless young (p. 51), which do not belong to the two preceding orders or the one next following. Beak without a cere. Three toes forwardly, one backwardly directed.

Group: =Hirundinidæ= (_Swallows_).

With short flat beak, broad at the base, with gape extending far back, and triangular as seen from above. In flight the beak is opened as widely as possible, serving for catching insects. Wings long and pointed. Feet short and weak, entirely unsuited or only poorly adapted for walking; their chief use is to enable the swallow to hold fast to different objects. Swallows fly quickly and catch insects while on the wing. The insects on which they prey are generally unimportant to agriculture and forestry; but they may also do good by catching crane flies (_Tipula_), and ribbon-footed corn flies (_Chlorops_), which often fly about our fields in enormous swarms in order to lay their eggs. All swallows are migratory birds. There belong here—

1. True =Swallows= (_Hirundo_), with forked tails; three toes directed to the front, one to the back. Here may be reckoned—=Swallow= (_H. rustica_), always broods in sheltered spots, _e.g._ inside a stable, summer-house, or verandah; =House Martin= (_H. urbica_), nests against buildings, under the eaves for example; the =Sand Martin= (_H. riparia_), breeds in the neighbourhood of streams, especially in vertical banks of loamy or coherent sandy soil, where it makes its nest at the end of a passage a yard long. The =House Martin= is shining black on the back, white on the entire under surface and rump. The =Bank Martin= is brownish grey on the back, white on the under side, with brownish-grey bands on the breast.

2. =Swifts= (_Cypselus_), with forked tails and four strong, curved, forwardly directed claws. Only one British species belongs here—the =Swift= (_Cypselus apus_), ten inches long, brownish black except for white throat, and with very long curved wings.

3. =Night-jars= (_Caprimulgus_), with tail not forked, soft plumage, large head and eyes; fly at night. One species belongs here—the =Goatsucker= (_Caprimulgus europæus_, Fig. 35), twelve inches long, grey on the upper side, spotted with blackish brown and rusty yellow, yellowish whitey grey with dark wavy lines on the under side. In the day it flies awkwardly and heavily, and usually keeps under cover; by night it flies rapidly and boldly, especially in bare spots in woods, or in gardens and on fields. It haunts especially the neighbourhood of sheepfolds and cattle in the meadows, since it always finds flies and gnats there. It also catches cockchafers and various moths.

[Illustration:

FIG. 35.—The Goatsucker (_Caprimulgus europæus_). ]

Group: =Magnirostres= (_Large-beaked Perching Birds_).

Beak strong, thick, often incurved near its apex. These birds eat almost all kinds of food, both animal and vegetable. Here belong Starlings and Raven-like Birds (crows, magpies, jays).

The =Starling= (_Sturnus vulgaris_).

Plumage black, with a violet sheen. The tips of the contour feathers, however, are white or bright yellowish. These white patches become so well marked after the autumn moult, that they almost completely cover the shining metallic black of the feathers. They gradually become smaller; in the next spring they are almost or entirely lost. Very serviceable. Devours, especially in autumn, many field snails, also cockchafer grubs, wireworms, grass caterpillars, grasshoppers, leaf-lice; also many insects destructive to fruit trees and forest trees. The starling, however, is able to do considerable damage to garden fruit trees, since it eats cherries, currants, and sometimes even pears. Starlings often settle on the backs of sheep and cows in order to pick off the vermin.

Genus: =Corvus= (_Crow-like Birds_).

Here belong—1. The =Jackdaw= (_C. monedula_), with relatively short beak and long tarsi. Black; side of the head and neck ashen grey. Breeds in holes in trees, chimneys, ruins, and towers. 2. The =Hooded Crow= (_G. cornix_); bright grey, except the head, throat, wings, and tail, which are black. Breeds in all parts of Europe east of the Elbe; occurs in Western Europe as a gipsy migrant in winter. 3. =Carrion Crow= (_C. corone_); black, beak stout and strongly bent at its end. Breeds in trees, but never (like the Rook) in large numbers together. 4. =Rook= (_C. frugilegus_); black, beak rather long; in adult specimens the head feathers are quite worn away at the base of the beak. 5. =Raven= (_C. corax_); much larger than the other species; black, beak very strong, strongly curved along its entire upper side. Nowhere in large numbers.

[Illustration:

FIG. 36.—Head of Rook (_Corvus frugilegus_). ]

_Food, Benefit conferred, and Damage done._ Ravens, and sometimes even rooks, attack lambs and sick sheep, also ducks, geese, fowls, and pigeons. Carrion crows and hooded crows rarely attack our domestic animals. All crows, however, steal the eggs of our poultry. They also injure sport, since they kill hares and rabbits, young fawns, quails, pheasants, etc. They do a little good, however, by devouring field-voles, but, as a rule, only catch the sick ones which are not able to move quickly. They do harm by destroying useful insect-eating birds, also eating their eggs and young. But as insect-eaters, they are extremely useful; they devour cockchafers, wireworms, butterflies, surface caterpillars, crane flies and their larvæ, and field snails; also many earthworms. As to the vegetable part of their food, they devour, in the first place, germinating seeds; grain, peas, beans. They also pick grain from the ear, both when ripe and, to a larger extent, when still soft; and in doing this pull down the ear so as to crack the stalk, thus causing more damage than by the mere eating. They also plunder the ripening peas, and feast upon cherries, plums, apricots, and other juicy fruits; even potatoes and turnips. All crow-like birds do some harm and some good, only the raven (which eats scarcely any insects) is to be always reckoned as an enemy.

The =Magpie= (_Pica caudata_) and =Jay= (_Garrulus glandarius_) are resident birds closely related to the crows. The first affects open tracts of land (fields, meadows, gardens) in the neighbourhood of large trees; the latter is a woodland bird. Both birds eat almost everything: grain, acorns, beechnuts, cherries, berries; cockchafers, wireworms, and similar insects; the eggs and young of useful insect-eating song-birds (such as titmice), also these little birds themselves, ducklings and chickens, young partridges, quails, pheasants, now and then field-voles. More harmful than useful.

Group: =Conirostres= (_Conical_-_beaked Perching Birds_).

Beak conical, thicker and shorter than in the species of the following group. They devour insects and seeds, a few species seeds exclusively. Here belong first the =Titmice= (_Parus_), gipsy migrants which are extremely serviceable both in fruit-tree culture and forestry. Then the =Larks= (especially the =Skylark=, _Alauda arvensis_, a resident), which nest on the ground, eating insects, seeds, and in winter even leaves; they feed their young, however, with insects. They do both good and harm, but the former mostly preponderates. In late summer and autumn, skylarks collect in flocks, and wander here and there for a long time: before this, they travel south; at this time many are caught and eaten. The male skylark sings beautifully, rising meanwhile high in the air. The =Buntings= (_Emberiza_) have a characteristic compressed and pointed beak; they seek their food on the ground in fields and meadows, and on roads. The food consists of grain and insects; but since these birds never take grains from the ear, they only do damage by picking them up at seed-time. They feed their young with insects. The damage is usually very inconsiderable, but, on the other hand, the benefit conferred is slight. (=Yellow Hammer=, _E. citrinella_, a yellow-coloured resident. The =Common Bunting=, _E. miliaria_, a grey-coloured migrant, etc.) In the family of =Finches= a number of species are included which are of small agricultural importance: _e.g._ the =Bullfinch= (_Pyrrhula vulgaris_), specially attacks fruit-tree buds in March; the =Goldfinch= (_Carduelis elegans_); the =Siskin= (_Chrysomitris spinus_); the =Lesser Redpoll= (_Linota linaria_); the =Greenfinch= (_Ligurinus chloris_). A few species, however, must be dealt with more fully, and, first,—

[Illustration:

FIG. 37.—Head of Bullfinch. ]

The two =Sparrows=,

_i.e._ the =House Sparrow= (_Passer domestica_) and the =Tree Sparrow= (_P. montana_).

=House Sparrow=: ear region bright grey. A rust-coloured or yellowish streak behind the eye. The whole throat black in the male. Wings with a yellowish white transverse band. =Tree Sparrow=: ear region black. A black streak behind the eye, a white band round the neck, and a black patch on the throat. Wings with two white transverse bands. The two sparrows are very much alike in their habits, but the house sparrow frequents more the neighbourhood of human dwellings, even in large towns. Both sparrows are mainly harmful; where seeds (especially those containing starch, _e.g._ corn) are available, they prefer this kind of food to any other; and, besides this, they chiefly bring up their young on soft unripe grain. Sparrows devour the germinating corn after seed-time, and also pick the grain from the ear, in which process they at the same time do damage by breaking down the haulms so that the grain falls out. They pick the young peas from their pods; devour, too, several juicy tree fruits, _e.g._ cherries and grapes; and destroy young garden seedlings, _e.g._ lettuce, spinach, garden flowers. The house sparrow eats more insects than the tree sparrow (among them—geometer caterpillars, injurious roller caterpillars), but leaves the most noxious kinds untouched. Both sparrows are residents, but in autumn and winter often collect together in large flocks.

The =Linnet= (_Linota cannabina_),

with grey-brown darkly spotted back. Belly whitish, tail black with broad white margins. During summer the top of the head and the breast of the male are of a beautiful red. They are often found together in flocks during September. In spring and summer they chiefly live on oil-containing seeds, and may even do some good by eating the seeds of charlock; usually, however, doing much more harm by devouring the seed of rape, flax, linseed, and hemp.

The =Chaffinch= (_Fringilla cœlebs_).

A white patch on the two outermost tail feathers and the ones next them. Wings with one white and one yellowish transverse band. Male: upper side of head and neck bluish grey, back brown, breast reddish brown. Female: back grey-brown, belly whitish, breast ash-grey. The chaffinch inhabits forests, both those of ordinary foliage trees and those consisting of conifers; it also nests in gardens and plantations. At the beginning of September the males separate from the females, and both sexes collect in large flocks which haunt gardens, avenues, and bushes. In mild winters they remain resident, but travel away if the cold is greater. The chaffinch devours oil-containing seeds by preference, but also eats starchy ones, and seeks its food on the ground. It does a great deal of damage in cornfields by picking the seeds out of the soil after they have been sown; but does not take the grain from the ear. It also eats young seedlings. But valuable services more than counterbalance the harm done. When the chaffinches in autumn fly about in large flocks in the fields, they eat an enormous number of weed seeds. The young are chiefly fed with insects, especially with caterpillars. In the spring, when the seeds have germinated and the young corn is not yet ripe, the chaffinch feeds itself also on insects.

Group: =Subulirostres= (_Awl-beaked Perching Birds_).

Beak slender, awl-shaped, round in transverse section. A fully developed organ of voice. Feed almost exclusively on insects; there are only a few species which occasionally eat seeds. A few of them, however, sometimes devour juicy fruits (cherries, bird-cherries, elder-berries, juniper-berries, grapes). The birds belonging to this group, without exception, feed their young on insects. They are of service; even those species which occasionally do damage are useful on the whole.

There belong to the Subulirostres—

The =Wagtails= (_Motacilla_), _e.g._ the =White Wagtail= (_M. alba_), usually living in the neighbourhood of water, and seeking its insect food in the fields (often behind the plough), and in pastures and gardens.

The lark-coloured =Pipits= (_Anthus_).

The =Hedge Accentor=, or “Sparrow” (_Accentor modularis_),—in garden hedges, and woods, feeding sometimes on seeds.

The following “warblers:” =Nightingale= (_Daulias luscinia_), =Robin= (_Erithacus rubecula_), =Redstart= (_Ruticilla phœnicurus_), the =Lesser Whitethroat= (_Sylvia curruca_), =Garden Warbler= (_S. hortensis_), =Willow Wren= (_S. trochilus_), =Chiffchaff= (_S. rufa_), =Reed Warblers= (_Acrocephalus streperus_ and _A. arundinacea_), etc. The last-named live among reeds and rushes on the banks of fresh waters, and eat insects which do not affect agriculture and forestry; all the other warblers are useful.

Other examples of the Subulirostres are the =Golden-crested Wren= (_Regulus cristatus_), and the =Common Wren= (_Troglodytes parvulus_), which are of service to forestry and fruit-tree culture, but not to agriculture.

[Illustration:

FIG. 38.—The Nightingale (_Daulias luscinia_). ]

Most of the native thrush-like birds (_Turdus_), _e.g._ the =Blackbird= (_T. merula_), the =Missel Thrush= (_T. viscivorus_), the =Fieldfare= (_T. pilaris_), the =Redwing= (_T. iliacus_), and the =Song Thrush= (_T. musicus_), assist the farmer by devouring noxious insects and snails; but several of them occasionally do damage by poaching on cherries, grapes, currants, etc. Some of them (_e.g._ the Song Thrush and Blackbird) breed in almost all parts of Britain, others come here only in autumn or winter.

ORDER: =Gyrantes= (DOVES).

Body strongly built, somewhat thick-set. Wings long and pointed. Beak weak, with a cere at its base; nostrils covered by gristly scales. Toes: three forwardly and one backwardly directed, free, _i.e._ without a web (as in poultry). The young are at first blind and naked. They are at first fed with a cheesy secretion of the glands of the crop; later, with grain softened in the crop. Doves always live in pairs. Nests careless, flat, of loosely arranged twigs; situated on tree-branches, rocks, and large buildings. Doves breed twice or thrice a year, laying two longish, shining white eggs.

Native British forms:—

[Illustration:

FIG. 39.—The Wood Pigeon (_Columba palumbus_). ]

1. =Wood Pigeon= (_Columba palumbus_, Fig. 39), from April to September scattered about in the woods, but after the breeding season wander about in flocks, and in winter travel further south, although many remain. It nests on horizontal branches, and feeds on seeds of fir and pine, acorns, beechnuts, also grain, peas, vetches, rape-seed,—but seeds of many weeds as well (_e.g._ those of charlock, vetchling, spurry, cleavers). When the earth is covered with snow it often eats cabbage and the leaves of winter rape, but is also of some service.

2. The =Turtle Dove= (_C. turtur_) occurs on the edges of woods, especially those consisting of coniferous trees. Nests in the trees. For _food_, _use_, and _harm_, cp. the preceding species. Steals buckwheat grains from the fields.

3. The =Rock Pigeon= (_C. livia_) is the original stock of our races of domestic pigeons. It nests, as a resident, in the Mediterranean countries; as a migrant, on the rocky parts of the coasts of Great Britain and the Orkneys, Shetlands, and Faroe Islands.

ORDER: =Rasores= (POULTRY).

Body strong, thick-set. Head small, often with naked, brightly coloured patches, with fleshy combs or with a crest of feathers. Tip of the upper beak bends over that of the lower one. No cere (cp. Doves). Wings short, rounded; flight heavy. Feet strong. Hinder toe small and usually attached to the tarsus higher up than the front toes. Claws blunt. A small web at the bases of the toes. The male of several species bears a spur on the tarsus. Birds of this order usually keep on the ground, scraping it in search of their food, which consists of seeds, berries, the green parts of plants, insects, worms, and snails. Young precocious (p. 51). Several domestic birds belong to the Rasores: pheasants, the various races of fowls, pea-fowls, guinea-fowls, turkeys.

The species living wild in Britain are game-birds. They are—the =Capercailzie= (_Tetrao urogallus_, Fig. 40), =Black Game= (_T. tetrix_), =Partridge= (_Perdix cinerea_), =Quail= (_P. coturnix_); none of them are particularly harmful or useful to agriculture.

The =Pheasant= (_Phasianus colchicus_, Fig. 41) was originally a native of the Caucasus, and shores of the Caspian Sea and Sea of Aral; it occurs wild in Central Europe. Pheasants are troublesome to the farmer, both by devouring the newly sown seed and by scratching up the fields.

[Illustration:

FIG. 40.—Male and Female Capercailzie (_Tetrao urogallus_). ]

ORDER: =Grallatores= (WADING-BIRDS).

The species here included differ very much among themselves; but all seek their food, which is almost exclusively of animal nature, at the water-edge (rivers, brooks, lakes, ditches, canals, seashore) or in damp places (damp meadows and ploughed fields, moors, swamps). They are, therefore, adapted to wading, and for this purpose have a long featherless tarsus, while the lower half of the long shank is quite bare and covered with horny scales. In flight the wading-birds do not draw their legs up to their body, as is the case with the birds already spoken of, but stretch them out behind to their full length. Monogamous. Young precocious (p. 51), except in storks and herons when they are nestlings. The shore-dwellers eat fish, bivalve molluscs, etc.; only those species living on damp meadows and fields are of use to agriculturists, by devouring insects, snails, and worms. These are indicated by the letter u in the following list of the commonest native kinds:—

[Illustration:

FIG. 41.—The Pheasant (_Phasianus colchicus_). ]

=Coot= (_Fulica atra_); =Water Hen= (_Gallinula chloropus_); =Corn Crake= (_Crex pratensis_, u); =Plovers= (_Charadrius_, u); =Pewit= or =Lapwing= (_Vanellus cristatus_, u); the =Snipes= (_Scolopax_); the =Curlews= (_Numenius_, u); the =Stints= (_Tringa_); the =Godwit= (_Limosa ægocephala_, u); the =Sandpipers= (_Totanus_, u); the =Heron= (_Ardea cinerea_).

[Illustration:

FIG. 42.—The Woodcock (_Scolopax rusticola_). ]

ORDER: =Natatores= (SWIMMING-BIRDS).

These birds are distinguished by their swimming powers and corresponding organization. Legs usually set on far back, shorter than the body. The feet in particular are adapted for swimming. In some swimming-birds each of the forwardly directed toes has a webbed margin (“split swimming feet,” Fig. 43); in others, the three front toes are all united by a web (Fig. 44), while the hind toe is either small or wanting (“swimming feet”); lastly, there are some in which all the toes are forwardly directed and united by a common web (“oar-feet”). The plumage of swimming-birds is compact, and always kept greasy by the secretion of the oil-gland. I shall speak of two families only.

Family: =Lamellirostra= (_Ducks_).

[Illustration:

FIG. 43.—Crested and Little Grebes (_Podiceps cristatus_ and _minor_). ]

The inner margin of the beak is covered by skin, thrown into transverse ridges or tooth-like projections. Swimming feet (Fig. 44). Tolerably long wings; remarkable powers of flight. Feathers soft. These birds mostly affect shallow fresh water, in which they get their food by grubbing in the mud, the soft skin of the beak serving as an organ of touch. Polygamous. Young precocious (p. 51).

Here belong—the long-necked =Swans= (_Cygnus_) and the thick short-necked =Geese= (_Anser_), in which the beak is higher than broad at its base; the =Swimming Ducks= (_Anas_) with broader beaks, the =Diving Ducks= (_Fuligula_), and =Goosanders= (_Mergus_) with a broad hanging web to the hind toe. None of these birds are useful, while wild geese and ducks are harmful.

[Illustration:

FIG. 44.—Goose (_Anser cinereus_). ]

Three species of wild =Geese= (=Grey Goose= = _Anser cinereus_, =Bean Goose= = _A. segetum_, =White-fronted Goose= = _A. albifrons_) chiefly breed in Eastern or Northern Europe, and only come to Britain in autumn or winter, flying about in flocks. They eat the grass in low-lying meadows, and even pull it up by the roots; in the cultivated fields they devour winter corn and winter rape, and tread down more with their clumsy feet than they eat. They are also harmful to vegetable growth, owing to the very caustic nature of their dung, which is often deposited in large quantities in one place. In regions where they breed they also devour both ripe and unripe grain. Where they only occur in autumn, they scrape potatoes, turnips, and carrots out of the ground in order to eat them. Flocks of geese fly in a slanting line or in the form of a ploughshare.

Among _Swimming Ducks_ damage is only done by the =Wild Duck= (_Anas boschas_). It breeds wherever there are fresh waters. Nests amongst grasses or swamp-plants, or in a tree. The wild ducks remain the whole winter as long as the waters are not frozen, otherwise they go off for a short time to the south. Food: the tops of stems, buds, leaves of various water-plants, also barley, oats, and other grain; water-insects, fish, and fish-spawn. These ducks also do damage in cornfields by treading down and cracking the plants.

Family: =Longipennes= (_Gulls_).

Usually swimming feet. Legs tolerably long, adapted for wading (Fig. 45). Wings long, pointed. Beak laterally compressed. Young nestlings (p. 51). Breed in larger or smaller flocks, usually on the coast, occasionally on the margin of fresh waters. They chiefly feed on fish, worms, molluscs, and crustacea; sometimes, in the case of a few species, on young birds and eggs, as well as mice and other small mammals. Gulls are usually of no importance in agriculture; but the =Black-headed Gull= (_Larus ridibundus_), which breeds on the banks of lakes and rivers, devours many cockchafers and other noxious insects. The =Herring Gull= (Fig. 45), =Kittiwake= (_Larus argentatus_ and _L. tridactylus_), and a few other species, which breed on the coast, sometimes show themselves inland, especially in stormy weather; they then pursue field-voles, and catch many injurious insects.

Besides the true =Gulls= (_Larus_), I will only mention the =Sea Swallows= (_Sterna_), with forked tails.

[Illustration:

FIG. 45.—Herring Gull (_Larus argentatus_). ]

Class III.: =Reptilia= (Reptiles).

Cold-blooded Vertebrates (p. 19). The heart has the same structure as in Mammals and Birds, but the left and right ventricles are usually only incompletely divided from one another (p. 20). The body is invested with horny scales or with bony plates covered by a horny layer. Reptiles are very unlike Birds in appearance, but present many essential points of resemblance to them in their skeleton; indeed, during earlier geological times, there were transitional forms between the two classes. The structure of the reptile egg, too, is very similar to that of the bird’s egg; but the first has no lime-salts deposited in its shell. The egg is not hatched out by the animal itself, but exposed to the heat of the sun or to the warmth developed by decaying vegetable matter. Several reptiles (adder, for example) keep their eggs in their bodies till the young escape. Reptiles have either no limbs (snakes, a few lizards), or, at any rate, the limbs are not well developed, and are so placed that the body does not rest upon them, but is slung between them.

[Illustration:

FIG. 46.—Common Lizard (_Lacerta agilis_); 2, head of the same from below; 3, tongue. ]

The Reptilia are divided into the Orders of =Crocodilia= (Crocodiles), =Chelonia= (Turtles and Tortoises), =Lacertilia= (Lizards), =Ophidia= (Snakes).

[Illustration:

FIG. 47.—The Adder (_Pelias berus_). ]

Our native reptiles have no agricultural importance. I will, however, briefly mention the =Adder= (_Pelias berus_, Fig. 47), as it is dangerous to man. Head broad; tail much smaller than the hinder end of the body. Colour greenish grey or brownish. A black zigzag band runs along the dorsal side of the body. Length about twenty inches. The two hook-shaped poison-fangs are found in the front of the upper jaw; opening the mouth widely causes them to be erected. They are traversed by poison-canals through which the poison flows immediately into the two bloodless wounds. The adder lives in woods and on mountain slopes, where it devours mice. The poison has a decomposing action on the blood; it causes fever, and swelling of the part bitten, as well as sometimes of the neighbouring parts. The bite may be fatal. Alcohol is spoken of very highly as a remedy.

[Illustration:

FIG. 48.—The Grass Snake (_Tropidonotus natrix_). ]

[Illustration:

FIG. 49.—Blindworm (_Anguis fragilis_). ]

The native =Ringed Snake= (_Tropidonotus natrix_, Fig. 48), three feet long, is bluish with belly flecked with black and white; a yellow and a black band on the neck. It is fond of going into the water, and eats frogs, newts, and insects. The =Smooth Snake= (_Coronella lævis_), two feet long, is brown, with black patches on the back, which, however, do not form a continuous band. Head dark velvety black. Devours lizards and blindworms. The =Blindworm= (_Anguis fragilis_) is indeed snake-like, or rather worm-like (Fig. 49), but nevertheless belongs to the lizards, with which its internal structure agrees.

Class IV.: =Amphibia= (Amphibians).

[Illustration:

FIG. 50.—Great Crested Newt (_Triton cristatus_); male above, female below. ]

Cold-blooded Vertebrates (p. 19). The heart has only one ventricle and two auricles (cp. p. 21). The skin is naked, damp, usually slippery and smooth; it helps in respiration. Although several Amphibians resemble various Reptiles in outward appearance (Newt and Lizard, Figs. 50 and 46), the structure of the skeleton is quite different. Upon the whole, Amphibians resemble fishes more closely, and they breathe by gills when they are young, which strengthens the agreement. They undergo a metamorphosis. The just-hatched young at first hold fast by suction to the jelly of the spawn; they have external gills. They quickly develop a membranous margin to the body, especially round the tail, which consequently forms a sort of oar. Meanwhile internal gills develop, and the external ones disappear. The larvæ are now fish-like (“tadpoles”). The limbs quickly grow out, the lungs develop, the tail shrivels up, and the animal leaves the water. Even the adult, however, lives among damp surroundings. In the adult state the Amphibians feed on insects, worms, and snails; many species are exceedingly useful owing to this.

Amphibians are divided into two orders, the _Urodela_ (Newts, etc.) and the _Anura_ (Frogs and Toads). To the first belong the =Great Crested Newt= (_Triton cristatus_) and the =Common Newt= (_Lissotriton tæniatus_). Examples of the Anura are the =Edible Frog= (_Rana esculenta_), the brownish =Common Frog= (_R. temporaria_, Fig. 51), the =Common Toad= (_Bufo vulgaris_), and the =Natterjack= (_B. calamita_, Fig. 52).

[Illustration:

FIG. 51.—Common Frog (_Rana temporaria_). ]

Both frogs and toads do good by devouring many noxious insects, and also, in particular, snails. Toads are often kept in greenhouses for this purpose; and in the research garden attached to the Rouen entomological laboratory the snails were entirely exterminated in 1891, as a result of introducing a hundred toads and ninety frogs.

[Illustration:

FIG. 52.—Natterjack (_Bufo calamita_). ]

Class V.: =Pisces= (Fishes).

Cold-blooded Vertebrates (p. 19), which breathe by gills during their whole life. The heart consists only of a single ventricle and a single auricle (p. 18). The head passes immediately into the body without any intervening neck. Fishes move chiefly by means of the tail, at the end of which there is a tail-fin. This and the dorsal and anal fins lie in the median plane of the fish, while the pectoral fins, which are attached to the skull in bony fishes, and also the ventral fins, are paired structures more or less comparable to the fore and hind limbs of higher vertebrates. The skeleton of most fishes (pike, perch, carp, eel, plaice) is bony; but in a few subdivisions of fishes (sharks, skates, sturgeons, lampreys) it is cartilaginous. The skin is usually covered with thin translucent scales; but there are fishes with a smooth skin (lampreys), with prickle-like dermal ossifications (sharks), and with rhomboidal bony plates (sturgeons). As Fishes are without exception aquatic, there is no need for me to treat more specially of them here.

[Illustration:

FIG. 53.—The Perch (_Perca fluviatilis_). ]

Second Sub-Kingdom: ARTHROPODA (JOINTED-LIMBED ANIMALS).

[Illustration:

FIG. 54.—Wood-borer (_Sirex_); 1, larva; 2, adult insect. ]

[Illustration:

FIG. 55.—The Large Centipede (_Scolopendra morsitans_). ]

[Illustration:

FIG. 56.—Ground Beetle, with nervous system drawn in white. ]

The body of an Arthropod is bilaterally symmetrical (cp. p. 16), and consists of a number of joints (Fig. 55), not equally numerous in all members of the sub-kingdom. These joints or segments lie one behind the other, and are at first alike; but as in the course of further development they become adapted to various functions, the difference between them becomes greater. Compare the Wood-borer represented in Fig. 54, 2, with the young form of the same animal (Fig. 54, 1). The segments often fuse together, which brings about the formation of a smaller number of subdivisions to the body; or even all the segments may become united (mites). In the last case the Arthropod characters are only to be seen in the jointing of the limbs. Segmented animals (_e.g._ the common earthworm) are also found among the worms (Sub-kingdom III. of the Animal Kingdom); but these worms have either no limbs, or only small unjointed foot-stumps, never jointed limbs as in the Arthropods. These last are limbless or with unjointed foot-stumps only when young; when adult they always have jointed limbs. The head of Arthropods bears several successive pairs of jaws, which move to and fro from one side towards the other. The covering of the body consists of hard protective pieces; it is only in the young condition that the skin of several species is soft. Arthropods have no internal skeleton; the muscles are attached to the skin. The central part of the nervous system (p. 10), which consists in Vertebrates of brain and spinal cord, lies in Arthropods almost entirely on the ventral side. In the head is situated the cerebral ganglion, a large nervous mass resting on the gullet, and giving off nerves to the eyes and feelers. Besides this, there is a ventral nervecord on the ventral side of the animal, running below the gut, and made up of several pairs of ganglia, united with one another by means of nerve fibres. The ganglia of the ventral cord send their nerves to the jaws, limbs, muscles, viscera, etc. The cerebral ganglion is connected with the first ventral ganglion by means of a cord on each side of the gullet (Fig. 56), so that a ring-like structure is formed. The breathing organs are gills in some Arthropods (the Crustacea, _e.g._ crayfish, crabs); insects and centipedes breathe by air-tubes or tracheæ, while the respiratory organs of spider-like animals, when these do not breathe entirely by means of the skin, are more or less strongly modified tracheæ. The structure of the tracheal system is generally as follows: on each side of the body there is a row of breathing-holes, or stigmata, through which the air can enter the tracheæ; these are very much branched, so that they finally become very fine tubes investing the various organs, which in this way obtain the requisite amount of oxygen. The stigmata on one side of a caterpillar are clearly shown in Fig. 60, and those of a hornet larva in Fig. 61.

Four classes belong to this sub-kingdom: Insecta (Insects), Myriapoda (centipedes, etc.), Arachnoidea (spiders, scorpions, etc.), Crustacea (crayfish, crabs, lobsters, etc.).

Class I.: =Insecta= (Insects).

[Illustration:

FIG. 57.—A Grasshopper, with the different regions of the body separated from one another. A, head; B, thorax: _I._, prothorax; _II._, mesothorax; _III._, metathorax; C, abdomen; _a_, antennæ; _b_, eyes; _c_, _d_, _e_, legs; _f_, _g_, wings; _p_, shank; _q_, foot. ]

Breathe by tracheæ (cp. p. 84). The segments fuse into three body regions (Fig. 57). These are—(1) the _Head_, bearing the eyes, feelers (antennæ), and jaws; (2) the _Thorax_, composed of three fused segments, of which the first (prothorax) bears a pair of legs, while the second (mesothorax) and third (metathorax) not only bear a pair of legs each, but also sometimes a pair of wings in addition; (3) the _Abdomen_, which possesses no limbs, and of which the number of segments is not always the same. These three regions of the body perform different functions; the head is concerned with sensation and the taking up of food, the thorax with movement, while the abdomen contains the organs of digestion and reproduction. I will now deal somewhat more fully with the different body regions of an insect.

_Head._—Almost all insects have in the adult state a compound eye, _i.e._ an eye made up of a large number (up to ten thousand) of smaller eyes. In many insects one finds in addition to this a few simple eyes on the top of the head. The feelers are very unlike in different insects; they serve as organs of touch, and perhaps also help some other sense. The mouth-parts consist of three pairs of jaws, of which the first (the mandibles) and the second pair (maxillæ) are freely movable from side to side, while the third consists of two jaws immovably fused together (lower lip, or labium). A downward projection of the skin of the head (the upper lip, or labrum) overhangs the three pairs of jaws (Fig. 58). In insects which feed on solid matters, tearing or chewing them, the jaws are short and sharp-edged (biting mouth-parts); in those which take up fluid food (blood, the juices of plants, etc.) they are elongated, and adapted for licking, sucking, or piercing.

[Illustration:

FIG. 58.—Head and Mouth-parts of a Ground Beetle, enlarged four times. A, from above; B, from below. _a_, labrum; _b_, mandible; _f_, maxilla with palpi (_g_); _c_, labium with palp (_e_). ]

_Thorax._—The names of the parts of the legs are for the most part those used in the case of mammalian limbs; though the similarity between the limbs of Mammals and Insects is quite superficial. The following parts are distinguished in the leg of an insect: (1) the generally spherical hip (_coxa_) (Fig. 59, _a_); (2) the very short _trochanter_ (_b_); (3) the elongated thigh (_femur_) (_c_); (4) the shank (_tibia_) provided with movable spines at its tip (_d_); (5) the three- to five-jointed foot (_tarsus_) (_e_), whose last joint ends in claws, and often also in flap-like outgrowths. The _Wings_ are expansions of the skin, which consist of two layers. There are tracheæ between the upper and lower lamellæ. At first (in the pupa) the wings are folded up; but the forcing of air into the tracheæ quickly causes them to