Part 1

AGRICULTURAL ZOOLOGY

BY

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. ]