When we once realise that whether in attacking or avoiding an enemy it is in most cases a great advantage to all animals to be hidden from view, and that each creature has arrived at this advantage by slow inheritance, so that their colours often exactly answer the purpose, how wonderful becomes the gray tint of the slug, the imitation of bark in the wings of the buff-tip moth, the green and brown hues of the eatable caterpillars, the white coat of the polar bear, and the changing colour of the arctic fox, the ermine, and the ptarmigan, as winter comes on! And when, on the other hand, we find badly-tasting creatures such as ladybirds and some butterflies, or stinging animals like bees and wasps, having bright colours, because it is an actual advantage to them to be known and avoided, we see that in studying colour alone we might spend a lifetime learning how the winners in life’s race are those best fitted for the circumstances under which they live, so that in ever-changing variety the most beautifully-adapted forms flourish and multiply.

Then if we turn to the skeleton and the less conspicuous framework of the body, the flippers of the whale, the manatee, or the seal, doing the work of a fish’s fin and yet having the bones of a hand and arm, reveal a whole history to us when we have once learned the secret that in the attempt to increase and multiply no device is left untried by any group of animals, and so every possible advantage is turned to account.

Next, the wonderful instincts taught by long experience give us a whole field of study. We see how frogs and reptiles, and even higher animals such as marmots, squirrels, shrews and bears, escape the cold and scarcity of food in winter by burying themselves in mud, or in holes of trees or caves of the earth till spring returns; and while we find alligators burying themselves in cold weather in America, we find crocodiles, on the contrary, taking their sleep in the hot dry weather in Egypt because then is their time of scarcity.

Then we learn that the birds avoid this difficulty of change of climate in quite another manner. They with their power of flight have learned to migrate, sometimes for short distances, sometimes for more than a thousand miles, so that they bring up their young ones in the cool north in summer, when caterpillars and soft young insects are at hand for their prey, and lead them in the winter to the sunny south where food and shelter in green trees are always to be found. So long indeed has this instinct of migration been at work, that often we are quite baffled in trying to understand why they take this or that particular route for their flight, because probably, when the first stragglers chose it, even the areas of land and water were not divided as now, so that we must study the whole history of the changing geography of the earth to understand the yearly route of the swallow or the stork.

And last but not least, when we look upon the whole animal creation as the result of the long working out of nature’s laws as laid down from the first by the Great Power of the Universe, what new pleasure we find in every sign of intelligence, affection, and devotion in the lower creatures! For these show that the difficulties and dangers of animal life have not only led to wonderfully-formed bodies, but also to higher and more sensitive natures; and that intelligence and love are often as useful weapons in fighting the battle of life as brute force and ferocity.

Even among the fish, which, as a rule, drop their eggs and leave them to their fate, we have exceptions in the nest-building sticklebacks and the snake-headed fish of Asia, which watch over and defend their fry till they are strong, in the pipe-fish where the fathers carry the young in a pouch, and in sharks which travel in pairs; while a pike has been known to watch for days at the spot where his mate was caught and taken away, and mackerel and herrings live in shoals and probably call to each other across the sea.

Among the other cold-blooded animals—the frogs, newts, and reptiles—it is true we find less show of feeling, but we must remember that these are only poor remaining fragments of large groups which have disappeared from the earth. Even among the amphibia however a tame toad will become attached to one person; while among reptiles, lizards are full of intelligence and affection, and snakes are well-known for their fondness for their owners. The case of the snake which died by its master’s side when he fell down insensible,[202] if it can be relied upon, would show that even cold-blooded animals have tender hearts.

Yet these are all instances of affection of lower animals to man. We must turn to the birds, that group which has gone on increasing in strength and numbers down to our day, to find that tender devotion which watches over the helpless nursling, defends the young at the risk of life, nay, like the peewit with the dragging wing, will even run in the

Footnote 202. Animal Intelligence, Romanes, p. 261.

face of death to lure the cruel destroyer away from the hidden nest. Natural history teems with examples of birds faithful to each other and pining even till death for the loss of a mate; while many birds, such as rooks, starlings, wild geese, swans, and cranes, not only live in companies and exact obedience from their members, but even set sentinels to watch, the duties of the office being faithfully fulfilled.

Then again it is to the higher animals, those nearer to ourselves, that we must look for the truest affection, and the strongest proofs of that obedience and sympathy which lead them to unite and so become strong in the face of danger. Among the beasts of prey it is true that, except the wolves and jackals, none herd together; but family love is strong and true. No tiger is so dangerous as is the mother tigress if any one approaches her young ones, or the lioness whose cubs are attacked, and in our own homes we all know the tenderness and devotion of a cat to her kittens. Nevertheless, these animals have very little social feeling; theirs are the narrower virtues of courage and fidelity to home, and to the duty of providing food for wife and children. It is among the gentler vegetable-feeders,—the antelopes and gazelles, the buffaloes, horses, elephants, and monkeys,—that we find the instinct of herding together for protection, and with this the consciousness of the duty of obedience and fidelity to the herd and to one another.

It is easy to see how this was necessary to protect these feebler animals from the attacks of their ferocious neighbours, and also what an advantage they had when they had once learned to set sentinels who understood the duty of watching while others fed, as in the case of the chamois and seals, of obeying the signal of a leader like the young baboons on the march, or of putting the mothers and children in the centre for protection, as horses and buffaloes do.

And there is a real significance in this gradual education in duty to others which we must not overlook, for it shows that one of the laws of life which is as strong, if not stronger, than the law of force and selfishness, is that of mutual help and dependence. Many good people have shrunk from the idea that we owe the beautiful diversity of animal life on our earth to the struggle for existence, or to the necessity that the best fitted should live, and the feeblest and least protected must die. They have felt that this makes life a cruelty, and the world a battlefield. This is true to a certain extent, for who will deny that in every life there is pain and suffering and struggle? But with this there is also love and gentleness, devotion and sacrifice for others, tender motherly and fatherly affection, true friendship, and a pleasure which consists in making others happy.

This we might have thought was a gift only to ourselves—an exception only found in the human race; now we see that it has been gradually developing throughout the whole animal world, and that the love of fathers and mothers for their young is one of the first and greatest weapons in fighting life’s battle. So we learn that after all, the struggle is not entirely one of cruelty or ferocity, but that the higher the animal life becomes, the more important is family love and the sense of affection for others, so that at last a fierce beast of prey with strength and sharp tools at his command, is foiled in attacking a weak young calf, because the elders of the herd gather round him, and the destroyer is kept at bay.

Surely then we have here a proof that, after all, the highest and most successful education which Life has given her children to fit them for winning the race is that “unity is strength;” while the law of love and duty beginning with parent and child and the ties of home life, and developing into the mutual affection of social animals, has been throughout a golden thread, strengthened by constant use in contending with the fiercer and more lawless instincts.

So it becomes evident that the beautiful virtue of self-devotion, one of the highest man can practise, has its roots in the very existence of life upon the earth. It may appear dimly at first,—it may take a hard mechanical form in such lowly creatures as insects, where we saw the bees and ants sacrificing all tender feelings to the good of the community. But in the backboned family it exists from the very first as the tender love of mother for child, of the father for his mate and her young ones, and so upwards to the defence of the tender ones of the herd by the strong and well-armed elders, till it has found its highest development in man himself.

Thus we arrive at the greatest and most important lesson that the study of nature affords us. It is interesting, most interesting, to trace the gradual evolution of numberless different forms, and see how each has become fitted for the life it has to live. It gives us courage to struggle on under difficulties when we see how patiently the lower animals meet the dangers and anxieties of their lives, and conquer or die in the struggle for existence. But far beyond all these is the great moral lesson taught at every step in the history of the development of the animal world, that amidst toil and suffering, struggle and death, the supreme law of life is the law of Self-devotion and Love.

INDEX.

References printed in Italics are to Figures in the Text.

Aard-vark, or Cape ant-eater, 202; * habits of, 203. * Adjutant bird killing the cobra, 121; * with its feet flat, 128. * Æpyornis of Madagascar, 140. * Affection in animals, 348–352. * Africa, aard-vark and pangolin of, 202; * darting birds of, 168; * isolation of, in ancient times, 340; * wild animals of, 275. * Air-bladder, uses and hindrances of an, 53; * of fish, use of, 26; * of minnow, 25; * of mud-fish, 55. * Air-breathers, home of the early, 70. * Air-breathing fish, 34. * Air-sacs in bones of birds, 135. * Alaska, sea-otters of, 301. * Albatross, habits of the, 146; * home of the, 147. * Aldabra, tortoises of, 101. * Aleutian Isles, sea-lions of the, 306, 310. * Alligators acting as scavengers, 109. * Alytes, a frog-father carrying strings of eggs, 87. * Amazons, manatees in the, 316; * monkeys of the, 246; * mud-fish of the, 33. * Amblystoma, air-breathing form of axolotl, 81. * America, absence of wild hogs in North, 263; * beaver communities of, 229; * earliest forms of horse come from, 265; * jaguar and puma of, 292; * passenger pigeons of, 162; * ant-bear of, 200; * characters of monkeys of, 245; * sturgeon in rivers of, 32; * songless perching-birds of, 169; * stags with single antlers in, 273. * American and Australian colonists, argument drawn from, 131. * Ammocœtes, history of, 18; * larva of lamprey, 16. * Amphibia, ancestors of the mammalia, 191; * large ancient, 82–84; * wonderful metamorphosis of, 335. * Amphibian, true meaning of the term, 77, 81. * Amphioxus lanceolatus, 11. * Ancestors of the higher milk-givers, 213. * Angling-fish, Lophius piscatorius, 59. * Animals, affection and devotion in, 348–352; * combination for defence among, 350; * narrow range of lower, 2; * which have taken to the water, 300; * living with early man in England, 343. * Anoplotherium, 209; * one of the ancestors of hogs and rhinoceroses, 213, 261. * Ant, limit of powers of the, 6. * Ant-bear of South America, 200; * habits and strength of, 204. * Antelopes, range of, 274; * setting sentinels, 269. * Antlers, gradual development of, 273. * Apteryx, or Kiwi, 140; * structure and habits of, 139. * Aquatic mammalia, 300. * Archæopteryx, or ancient winged bird, 129, 131; * restoration of, 153. * Arctocyon, 209; * ancestor of carnivores, 213. * Arm, modifications of the, 347. * Armadilloes, with plates like a crocodile, 204; * figured, 200. * Ascidian, growth of an, 14. * Ass, skeleton of a wild, 266. * Australia, bats and mice in, 230; * duck-billed platypus of, 187; * isolation of, 340; * mud-fish of, 33; * why the home of marsupials, 185. * Australian marsupials, 193. * Australian and American colonists, argument drawn from, 131. * Axolotl and amblystoma, 80. * Axolotl, metamorphosis of, into amblystoma, 81. * Aye-aye, habits of the, 245; * figured, 244. * Babirusa, a double-tusked hog, 262. * Baboon, fetching a young one, 250; * structure and habits of, 249. * Backbone, first start of a, 12; * of the minnow, 24. * Backboned division, 3; * advantage of skeleton in the, 7; * lowest form of the, 10–15. * Badgers, small carnivores, 281. * Bandicoots, marsupial rabbit-rats, 195. * Bangsrings, insect-eaters, 232. * Barbets, climbing birds, 165. * Basking shark, 28. * Bat, flying, 220; * long-eared, 236; * skeleton of a, 233; * walking, 235. * Bats, structure and habits of, 233–237; * affection for young, 238; * enemies of, 236; * fruit-, in Mauritius, 238; * the only true flying milk-givers, 232–237; * self-guiding power of, 234; * vast masses in caves, 236. * Bear, hug of the, 295; * grizzly, an animal feeder, 295; * Polar, 294; * food of, 293; * habits of, 296. * Bears, largely vegetarian, 293; * walk flat-footed, 294. * Beaver, 227; * structure and habits of the, 228. * Beaver-meadows, 229. * Beckles cited, 212. * Bee-eaters of Africa, 168. * Beryx, a deep-sea fish, 43, 47, 50. * Bichir of the Nile, 33. * Bird, the structure of a, 124–129. * Bird-life as a whole, 179. * Birds, ancient, 123, 153; * with jointed tails, 130; * with teeth, 130; * arose not direct from reptiles but from a common ancient stock, 131; * avoiding winter by migration, 348; * climbing, 162; * dangers of land, 154–156; * darting, 167; * feet of perching, 155; * ground, 156; * a group of wading, 149; * growth of feathers of, 133; * habits of scratching, 156; * linked in structure to reptiles, 129; * love-time of the, 124; * lungs of, 135; * migrations of, 142, 151, 155, 177; * mound-building, 158; * nest-building, 170; * origin of, 337; * perching, 168; * of prey, 174; * range of, 136; * rise from ground to perching, 159; * running, 136–140; * sea, 142; * singing, 168; * songless, 169; * structure of water-, 141; * third eyelid of, 136; * throat of singing, 169; * wading, 148; * warmer-blooded than man, 135; * wingless, 139. * Bisons, protecting a young one, 269; * the only ruminants of America, 274. * Blennies, walking-fish, 57. * Blue shark, Carcharias glaucus, 29. * Boa constrictor of America, 115; * manner of seizing and devouring prey, 117. * Boar, defences of the wild, 260. * “Bombay Duck” a phosphorescent fish, 48; * figured, see frontispiece. * Bone at tip of mole’s nose, 224. * Bonito, a fish without air-bladder, 53. * Bony fish, agility of, 44; * or modern fish, 27; * early forms of, 43; * origin of, 45; * rise and spread of, 43; * structure of, 45. * Bony pike of North America, 33. * Box-tortoises closing their shell, 101. * Brazil, monkeys of, 246. * Breast-bone, flat in running birds, 136; * keeled of flying birds, 124. * Breathing apparatus of birds, 135; * of bony fish, 45; * of frog, 75, 76; * of lamprey, 17; * of lancelet, 12; * of marsupials, 192; * of minnow, 23; * of mud-fish, 34; * of seals, 308; * of shark, 30; * of the snake, 113; * of sturgeon, 32; * of tadpole, 73, 74; * of tortoise, 95; * of whales, 321. * British Museums, specimens in, 32, 34. * Brush-turkeys and their mounds, 158. * Buffalo cow defending her calf, 274. * Buzzard killing a viper, 120. * Cæcilians, nearest type to Labyrinthodonts, 84; * worm-like amphibians, 82. * Calf-fish or amia, 33. * California, sea-otters of, 301. * Californian gray whale in ice, 330; * killed by a shoal of grampuses, 325. * Camel, 270; * the only ruminant with upper front teeth, 270. * Capybaras of South America, 215. * Carapace of tortoise, 98. * Carnivora, or flesh-feeders, 257, 259; * ancestors of the, 213; * the smaller, 280. * Carnivorous marsupials, 196. * Carp family, 65. * Cartilaginous fish, 31–42. * Cassowary of New Guinea, 139. * Cat-fish, 65. * Cat less tamable than dog, 287. * Cave-lion in England, 343. * Celebes, double-tusked hog of, 262. * Ceratodus or “Barramunda,” 34; * a descendant of ancient fish, 39. * Chalk Period, extinction of reptiles in the, 211. * Chamæleon, 105; * structure and habits of, 106, 107. * Chauliodus, a deep-sea fish, 47; * figured, see frontispiece. * Chauvin, Marie von, cited, 81. * Chimæra between sharks and sturgeons, 41. * Chimpanzee, home of the, 253. * Chinchillas of South America, 225. * Circulation of blood in frog, 76. * Clavelina, larval form of, 14. * Claws, retractile of felines, 289. * Climbing birds, paired toes of the, 163; * build in tree-holes, 164. * Clinging fish, 51, 57, 58. * Coal-forests, amphibians of the, 82. * Coast fish, 57. * Cobra, enemies of the, 121. * Cobra di Capello, 118. * Cold blood, the cause of, in the frog, 76. * Cold-blooded life in reptiles, 90; * cold-blooded vertebrates, 24. * Colours, protective, 347. * Colugo, a flying insect-eater, 231. * Conger eels, 49. * Conodonts, probably lamprey’s teeth, 19. * Cope, Prof., cited, 212, 190. * Cormorant, figured, 144. * Coryphæna or dorado, 53. * Cow chewing the cud, 259. * Cranes, migrations of, 152. * Creation a gradual change, 336. * Creepers, 172. * Creative power, ever silent working of the, 336; * high conception of the, 345. * Crocodile, 108; * care for her young, 110; * habits and structure of the, 108. * Crop of pigeons, 161. * Crustaceans, huge, in time of early fish, 37. * Cuckoo, sometimes builds a nest, 166. * Cud, chewing the, 259. * Cumberland, Mr., on vitality of ant-bear, 205. * Curlews, wading birds, 148. * Cyclostomata, round-mouthed fishes, 16. * Dace, 65. * Dactylopterus, or flying gurnards, 55. * Darwin, on blood-sucking bats, 237; * on Galapagos tortoises, 101; * on evolution, 345. * D’Azara on ant-bear, 205. * Deep-sea fish, 47–50; * rising at night, 50. * Deer, growth of antlers of, 271; * range of, 273. * Depth at which fish live, 49. * Desman, 226. * Devotion in animals, 348–352. * Dingo dog, probably brought to Australia, 194. * Dinichthys, a huge Devonian fish, 40. * Dinocerata, ancestors of elephants and hoofed animals, 260. * Dinornis, extinct wingless bird, 140. * Dipper, or water-ouzel, 172. * Dipterus, a large ancient fish, 39. * Disk of the Remora, 52. * Dodo, flat-breasted pigeon, 161. * Dog, descended from wolves and jackals, 286. * Dogfish, 28. * Dolphins travel in shoals, 323. * Dorado pursuing flying-fish, 54. * Doras, a land-travelling fish, 66. * Dromatherium, jaw of, 183. * Duck, structure of the, 141. * Duck-billed platypus and its home, 188; * the lowest type of milk-giver, 188. * Dugong, a tusked sea-cow, 314. * Dunlins, wading-birds, 148. * Eagle bringing food to its young, 175. * Eared-seals, history of the, 310. * Echidna, 188; * a low milk-giver, 190. * Edentata, low and antiquated forms, 201; * former history of, 201. * Eels and eel-fares, 66. * Efts, huge, of olden times, 82; * or newts of our ponds, 78. * Egg-birth, dangers of, 184. * Eggs, of the crocodile, 110; * of fish carried in the father’s mouth, 65; * of frogs, 71; * of ostriches cracked by the father, 139; * of fish, modes of transport of, 66; * of shark, 28, 42; * of snake, 116. * Eider-duck, range of the, 142. * Elastic band in front of snake’s jaw, 111. * Elephant, affinity to rodents, 276; * the Indian, 277; * intelligence of the, 278; * structure of the, 276–279; * tooth and tusk of, found in Australia, 194; * -seal, 314. * Emus, pairing birds, 139. * Enamel-scaled fish, 33. * Eohippus, 209; * ancestor of the horse, 213, 261. * Europe in the age of ice, 299. * Evolution, of sympathy and self-sacrifice, 352; * taught by Darwin, 345. * Exocœtus, the flying-fish, 54. * Eyelid, third, in reptiles and birds, 109, 136. * Eyelids, absence of, distinguishes snakes from legless lizards, 110. * Falcon, swooping of the, 176. * Fangs of poisonous snakes, 119. * Feather, number of threads in an eagle’s, 133. * Feathers of birds, their growth and importance, 133, 134. * Feet, grasping of perching birds, 155. * Felines, highest type of flesh-feeder, 290; * kill by a blow, 288; * retractile claws of, 289. * Fins of the minnow, 24. * Fish, affection shown by, 69; * age of the gristly, 333; * air-bladder of, 25; * ancient forms of, 33, 37–42; * blind, of Kentucky caves, 68; * come to the coast to spawn, 57; * deep-sea, 47–50; * lowest type of, 11; * limbs of, 25; * mammals which imitate, 318; * muscular power of, 24; * ocean home of the, 21; * of the old or gristly type, 27; * parental care in, 349; * skeletons of deep-sea, 49; * small ancient, 20, 34–42; * varieties of modern, 46; * weapons of, 29, 40, 42, 48, 52, 58, 59, 64, 68. * Fishing frog, Lophius, 59. * Fish-life, general sketch of, 67. * Fish-lizards of olden times, 92. * Flamingo, half-way between waders and swimmers, 150. * Flat-fish, structure of, 61. * Flint tools of early man, 343. * Flying-fish, 53–55. * Flying-gurnards, 55. * Food of land-birds, 155. * Fowls and their relations, 157. * Fox, a solitary hunter, 285; * range of the, 286. * France, tree-frogs of, 87. * Freshwater fish, 65. * Frigate-bird, perches on trees, 148. * Frog, a recent form of amphibian, 84; * carrying young in a pouch, 87; * carrying eggs and tadpoles, 87; * metamorphosis of the, 72–76; * lungs of, 76; * more nearly allied to fish than reptiles, 129; * mouth and tongue of, 77; * respiring skin of, 77; * spawn described, 71; * tree-, of New Guinea, 86. * Fruit-bats, 238. * Fur-seals, history of, 310. * Gadow, Dr., on number of threads in an eagle’s feather, 133. * Galagos or lemurs of Africa, 243. * Galapagos, tortoises of, 101. * Galeopithecus or Colugo, 231. * Gaudry cited, 212. * Gautier, M., on snake poison, 119. * Gecko or wall lizard, 105. * Geese, range of wild, 142. * Geography, changes in physical, 340. * Germany, beaver communities in, 229. * Gibbons, or long-armed apes, 251. * Gibraltar, monkeys on the rock of, 241. * Gills of Axolotl, 80; * of bony fish, 45; * of embryo shark, 73; * of the minnow, 22; * of proteus, 79; * of sea-horse, 63; * of shark, 30; * of sturgeon, 32; * of tadpole, 73. * Giraffes, structure of, 271. * Glacial Period, 342. * Glass-snake of America, 107. * Globe-fish, 55. * Glyptodons, ancient armadilloes, 202, 208. * Goats and sheep, range of, 274. * Gobies, clinging by the throat, 58. * Golden age of amphibia, 83; * of ancient fish, 40; * of reptiles, 92. * Gorilla, at home, 254; * driving out elephant, 251; * structure and habits of, 253. * Grampus, a flesh-feeding whale, 325. * Gray, Capt., on whalebone, 329. * Greek tortoise, 96; * killed by birds, 101. * Greenland whale, traces of hind limbs in the, 318. * Gristly skeleton of shark, 31. * Ground-birds, 156–161; * generally polygamous, 161. * Ground-pigeons of New Guinea, 161. * Grouse are ground-nesters, 156. * Gudgeon, 65. * Guillemots, homes of the, 144; * silvery bubbles on, 143. * Gulls and their homes, 144. * Günther, Dr., on deep-sea fish, 49. * Gurnards walking, 57. * Haddock, destroyed by hags, 18. * Haddon, Prof., A.C., drawings by, 11, 14, 23. * Hadrosaurus, 93. * Hags or borers, 16, 18. * Hang-nests of America, 173. * Harpodon, a deep-sea fish, 47; * figured, see frontispiece. * Harvest-mouse and shrew compared, 218. * Hawksbill turtle, tortoise-shell of, 97. * Hearing apparatus of herrings, 56. * Heart, of amphibia and reptiles, 74, 76, 96; * of birds, 135; * of fishes, 23; * of frog, three-chambered, 76; * of tadpole, two-chambered, 74; * three-chambered, of tortoise, 96. * Hedgehog, 220; * structure and habits of, 220. * Herbivora, ancestors of the, 213; * advantage of struggle for existence to the, 282; * defences of the, 259; * large stomachs of, 258; * structure of the, 258; * uniting for defence, 350; * wide range of, 257. * Heron, strokes of wing of, 134; * a tree-building wader, 152; * grasping foot of the, 152. * Herrings probably call to each other, 56; * their habits and structure, 56. * Hesperornis, 130; * figured, 123. * Heterocercal tails, 30. * Hippocampus or sea-horse, 63. * Hippopotamus, defences of the, 263; * former range of the, 263; * in glacial beds, 342. * Hissing of a snake, how caused, 113. * Hogs, early types without tusks, 260; * various kinds of, 263. * Homocercal tails, 30. * Hoofs as defences, 260. * Horns, absence of, in early forms, 260; * as defences, 260; * permanent, of buffaloes, 273. * Horse, ancestors of the, 213, 261; * genealogy of the, 267; * mouth of the, 259; * no true wild living, 265; * structure of the, 259, 266. * Horses unite for protection, 268. * Howler-monkeys, 246. * Humming-birds, lovely nests of, 167. * Humpback whale suckling her young, 319. * Huxley on Ichthyopsida and Sauropsida, 129. * Hyæna, in glacial times of England, 342; * teeth and claws of the, 290. * Ice, covering Northern Europe, 342. * Ichneumon, killing the cobra, 121; * the Egyptian, 281. * Ichthyodorulites of the Silurian, 38. * Ichthyopsida, fish and amphibia, 129. * Ichthyornis, 130; * figured, 123. * Ichthyosaurus, 89, 92. * Iguanas or tree-lizards, 106. * Iguanodon, 89, 93. * Imperfect-toothed animals, or Edentata, early history of, 201. * Insect-eater, skull and teeth of, 217. * Insect-eaters, a group of, 220; * small-sized animals, 215; * and rodents compared, 239; * absent from South America, 230. * Instincts, interest of in theory of development, 347. * Invertebrata and their limits, 4–6, 9. * Isinglass from sturgeon, 32. * Jacamars of America, 168. * Jackals, hunting in packs, 285; * ancestors of the dog, 286. * Jaguar, feeding on tortoise, 100; * habits and range of the, 292; * and ant-bear, 205. * Japan, gigantic salamander of, 78; * monkeys in, 241. * Jaw, movement of, in flesh-feeders, 289; * in vegetable-feeders, 259; * of snake, 119; * distensible, 114. * Jerboas of Africa, 225. * Jumping shrews, 225. * Kangaroo-rats, 195. * Kangaroos, 193; * strength of, 194. * Kentucky caves, blind fish of, 68. * Kaola, or native bear of Australia, 193, 195. * Killer-whale, voracity of the, 325. * Kingfisher, 166; * a darting bird, 167. * “King of the Herrings,” 41. * Knob, on bird’s beak for shell-breaking, 143; * on nose of baby platypus, 190. * Labyrinthodonts, age of, 337; * of the coal-forests, 84. * Lakes, fish-eggs carried to, 66. * Lamprey, and young, 16; * breathing organ of, 17; * teeth of, 17, 19, 37; * metamorphosis of the, 19. * Lampris luna, sun-fish, 53. * Lancelet, structure of the, 11. * Land-birds, their enemies and difficulties, 154–156. * Lark, nest of the, 170. * Legs, of a bird, construction of, 127; * vestiges of, in snakes, 110. * Leidy cited, 212. * Lemming, strange migrations of, 225. * Lemurs, 244; * position and habits of, 243. * Lepidosteus or bony pike, 33. * Life, gradual development of, 4. * Light-giving deep-sea fishes, 47. * Lion fighting with a buffalo, 274; * formerly in England, 291; * habits and range of the, 291. * Lizard, skeleton of a, 103; * structure and habits of, 104; * can live in unhealthy places, 104; * flying, 106; * legless and snake-like, 107. * London, hippopotamus bones under, 263. * Lories, the lemurs of India, 243. * Love, gradual development of parental, 348–350; * a reigning law of life, 353. * Lumpsucker clinging to rock, 58. * Lungs, of frog, 76; * of the snake, 113. * Machairodus or sabre-toothed tiger, 291; * figured, 333. * Mackerel going in to spawn, 55. * Madagascar, true lemurs of, 243. * Magpie’s nest, 170. * Mammalia or milk-givers, divisions of the, 182; * distribution of, 340; * aquatic, 300; * extinction of large, 341; * sudden appearance of higher, 211. * Mammoth, the hairy, 279. * Man, after Glacial Period, 343; * among animals now extinct, 333; * exterminating wild animals, 344. * Manatee or sea-cow grazing, 315; * relationship of, 303. * Mandrill, the lowest baboon, 250. * Manis or pangolin, 202; * structure and habits of, 203. * Marmosets, monkeys of South America, 245. * Marmot, a burrowing rodent, 225. * Marsh, Prof., his collection of reptile remains, 339; * cited, 212; * on Dinocerata, 260. * Marsupials, jaws of earliest known, 183; * breathing of infant, 192; * of Australia, past history of the, 185; * early appearance of, 337; * playing the part of higher animals, 196; * structure and habits of, 192–199. * Mastodon, a four-tusked elephant, 279; * figured, 256. * Megalosaurus, 93; * figured, 89. * Megapodes, mound-building birds, 159. * Megatheria, huge ancient ground-sloths, 202, 206, 208. * Metamorphosis of the frog, 73–76. * Mexico, iguanas of, 106. * Microlestes, tooth of, 183. * Migration, of birds, 142, 151, 155, 177, 348; * of lemmings, 225. * Milk-givers are viviparous, 185; * earliest origin of, 191; * extinction of large, 341; * home of the early, 181; * sudden appearance of higher, 211; * taking to the water, 300. * Miller’s thumbs, 65. * Minnow, breathing apparatus of the, 22; * inner and outer structure of the, 23–26; * intelligence of, 26; * spinal cord of, 23, 26. * Moa of New Zealand, 140. * Mole, 220; * enemies of the, 224; * structure and habits of, 223. * Mole-rats, burrowing rodents, 226. * Monitors of Africa, 105. * Monkeys, 247; * advantage of tree-life to, 251; * almost confined to hot countries, 241; * grasping hands and feet of, 241; * intelligence of, 248; * origin of, 240; * of America, 245; * of the Old World, characters of, 248. * Monk-fish, 41. * Moor-hen, intelligence of the, 151. * Mosasaurus, 92; * figured, 89. * Motmots of America, 168. * Mound-building birds, 158. * Mucous scales of fish, 23, 27. * Mud-fish and their breathing, 33. * Mud-tortoises, 102. * Mullets, feeding, 57. * Musquash, a swimming rodent, 227. * Myrmecobius, an insect-eating marsupial, 195; * like the ancient marsupials, 198. * “Native Devil” or Dasyurus, 197. * Nervous system of vertebrata, 8. * Nest of the common wren, 171; * of duck-billed platypus, 188. * Nest-building birds, 168–173; * gradual progress of, 156, 160, 165, 167, 170, 173. * Nests, edible, of China swiftlet, 167; * inland, of wading birds, 151. * Newts, 78. * New Zealand, wingless birds of, 140. * Nightjar hunting for prey, 167. * Nile, crocodile of the, 108; * mud-fish of the, 33. * Norway, lemmings of, 225. * Nostrils of fish, 27. * Notochord of the lancelet, 12. * Nototrema frog, with a pouch for young, 87. * Nuthatch, a climber among perchers, 172. * Opossums, 200; * habits of, 198; * why surviving in South America, 197–199: * their relation to Australian marsupials, 198. * Orangutan or mias, 252. * Orca or grampus, a flesh-feeding whale, 325. * Ornithorhynchus, and its home, 188; * bill and feet of, 189; * structure of the, 190; * the lowest milk-giver, 191. * Osprey, the sea-eagle, 177. * Ostrich at full speed, 137; * structure and habits of, 138. * Otter, common, 301; * sea-, 302. * Owen, Prof., on a reptile like platypus, 190; * on advantage of pouch to marsupials, 193. * Owl, adapted for night-hunting, 176. * Owl-monkeys, 246. * Oystercatchers, wading birds, 148. * Paddle-fins of mud-fish, 35, 38. * Paleotherium, 209; * one of the ancestors of tapirs and rhinoceroses, 213, 261. * Pallas cited, 11. * Pangolins, structure and habits of, 203. * Paraguay, rheas of, 139. * Parker, Prof. Kitchen, on evolution, 191; * on origin of mammalia, 191. * Parkyn, Mr., on baboons, 249. * Parrots, using beak in climbing, 165. * Partridges, ground-nesters, 156. * Peccaries of South America, 263. * Peewit or lapwing, 148. * Pelican, perches on trees, 148. * Penguin, home of the, 147; * swimming wings of the, 146. * Perch, climbing, 66. * Perching birds, 168–173; * aquatic bird among, 172; * bird of prey among, 172; * climbers among, 172; * darters among, 172; * ground-feeders among, 170. * Petrel, home of the stormy, 145. * Phalanger, a flying, 193, 195. * Pheasants, ground-nesters, 156. * Phosphorescent, fish, 47, 48; * fluid, 50. * Pigeons, beginners in nest-building, 160; * crop of, 161; * passenger, 162. * Pike, 65. * Pilot-fish accompanying shark, 52. * Pipistrelle the common bat, 236. * Plates, horny, in duck’s bill, 142; * in bill of Ornithorhynchus, 188; * in mouth of whale, 328; * under the snake’s body, used in walking, 112. * Platypus, 188; * knob on nose of baby, 190. * Plesiosaurus, 92; * figured, 89. * Plovers, wading birds, 148; * dragging the wing, 151. * Pocket-mice of North America, 215. * Poison of snakes a concentration of a substance found in ordinary saliva, 119. * Poisonous snakes, 117–121. * Polar bear, walrus fighting the, 309. * Polypterus or bichir, 33. * Porcupine, 221; * structure and habits of, 222; * tree, 222. * Porpoise, 323; * good type of whales, 324. * Pouch-bearers, see Marsupials. * Pouched-rats, burrowing rodents, 226. * Prairie-dogs, burrowing rodents, 225. * Protective, colours, 347; * smells in animals, 347. * Proteus of Carniola caverns, 79. * Protopterus of the Nile, 33. * Protorosaurus earliest known reptile, 91. * Ptarmigan, white plumage of, 157. * Pterodactyls or flying reptiles, 93; * figured, 89. * Pterygotus and early fish, 37; * figured, 20. * Puff-birds of America, 168. * Puffin Island, sea-birds of, 142. * Puffins, 144; * laying eggs in cliff-holes, 142. * Puma, range and habits of the, 292. * Pythons crushing their prey, 117. * Quadrate bone, absent in milk-givers, 191; * giving a wide gape to the snake, 114; * in bird, 126; * in lizard, 103; * in snake, 111. * Quadrumana, use of term, 242. * Quails, scratching birds, 157. * Queensland, Ceratodus of, 34. * Rats, intelligence of, 230. * Rattlesnake feeding on “Prairie dogs,” 225; * horny plates of the, 118; * jaw of the, 119. * Rays, manner of feeding of, 42. * Red deer with branching antlers, 272. * Remora carried by shark, 51. * Reptiles, abound in warm countries, 90; * age of the great, 339; * care for their young, 122; * disappearance of ancient, 94, 211; * flying, of olden times, 93; * huge, of ancient times, 91, 94; * in their palmy days, 89; * lay their eggs on land, 90; * linked in structure with birds, 129; * modern, 94–122. * Rheas, three-toed ostriches, 139. * Rhinoceros, absence of upper teeth in, 265; * horn made of matted hair, 264; * embedded in ice, 265. * Rhytinas in Behring’s Straits, 316. * Ribbon fish, 49. * Ribs of lizard, 97, 103; * of snake, used in walking, 112; * of tortoise, forming the shell, 99. * River-fish, 46, 64. * River-tortoises, 101. * Roach, 65. * Rodent, skull of, 217; * teeth of, 216. * Rodents or gnawers, 215; * affinity of elephants to, 276; * generally small and weak, 215; * a group of, 221; * and insect-eaters compared, 239. * Rollers, darting birds of the East, 168. * Rooks, nests of, 170. * Rorqual, short whalebones of, 326. * Rough hound, 28. * Round-mouthed fishes, 16. * Ruminants, characters of the, 259; * wide spread of, 269. * Running birds, 136–140. * Russia, sturgeon in, 32. * Salamander, gigantic, of Japan, 78; * black, viviparous, 81. * Salamandra atra, viviparous, 81. * Salmon going up river to spawn, 64. * Sandpipers, wading birds, 148. * Sauropsida, birds and lizards, 129. * Scales of bony fish and mud-fish, 45; * of fish, 27; * of snakes embedded in the skin, 111. * Scaly lizard is viviparous, 105. * Scoresby, on walrus killing narwhal, 309; * on whale-mothers defending their young, 330; * on whale spouting, 321. * Sea, chief home of fish, 46. * Sea-birds, 142–150; * a group of, 144. * Sea-cows, relationship of, 303; * their structure and habits, 315. * Sea-horse, a fish, 63. * Sea-lion, and common seal, 306; * skeleton of a, 304; * structure of, 305; * range of, 306. * Sea-lions on the Aleutian Isles, 310; * fighting for wives, 311. * Seals, breathing apparatus of, 308; * how adapted for a sea-life, 307; * on English coasts, 303; * origin of, 303; * structure and range of, 313, 314. * Seal-skin, how prepared, 308. * Sea-otter, structure of the, 301. * Sea-squirt, growth of a, 14. * Sea-squirts, anomalous position of, 15. * Sea-tortoises coming on land to lay eggs, 102. * Secretary bird killing poisonous snakes, 121. * Self-sacrifice, a law of life, 352. * Sentinels placed by animals, 269. * Shark carrying remora, 51; * accompanied by pilot-fish, 52; * eggs, 28, 42; * external gills of embryo, 73. * Sharks, history of the, 41; * their structure, 28–30. * Sheat-fish, fathers carrying eggs in the mouth, 65. * Sheep and goats, range of, 274. * Shell of tortoise, how formed, 98. * Shields of the crocodile, 108. * Shrike, a perching bird of prey, 172. * Shrew and harvest-mouse compared, 218. * Silver Pit, soles living in the, 63. * Siren, a gill-breather, 80. * Sirenia, name for sea-cows, 315. * Skates, flat bodies of, 41; * purse-eggs of, 42. * Skeleton, of bat, 233; * bird, 126; * wild ass, 266; * lizard, 103; * sea-lion, 304; * snake, 111; * tortoise, 98; * whale, 318. * Skeletons of deep-sea fish, 49. * Skulls of rodent and insectivore, 217. * Skye, walrus seen off, 310. * Slime on fish causing phosphorescence, 50. * Sloths hanging from a tree, 200; * structure and habits of, 206. * Slowworm, a legless lizard, 107. * Smooth hound, 28. * Snake, affection in a, 349; * casting its skin, 116; * common ringed, 113; * cup and ball joints of the, 112, 114; * eggs, 116; * enemies of the, 117; * food of the common, 116; * mode of swallowing prey, 114; * skeleton of a, 111; * coiling round prey, 117; * nature of poison of, 119; * poisonous sea-, 121. * Snapping turtle, 101. * Sole, history of its growth, 62; * young and old, 61. * Song of birds, how caused, 169. * Sparrow, 125; * skeleton of, 126. * Spawning of lampreys, 18. * Spermaceti in head of whale, 326. * Sperm whale, 327; * its structure and habits, 325; * taking breath, 322. * Spider monkeys, 246. * Spinal cord, of lamprey, 17; * of the lancelet, 12; * of shark, 30; * of vertebrata, 9. * Spines, of hedgehog and porcupine, 222; * of sharks, 29, 38. * Spinous processes, of lizard, 103; * of snake, 111; * of tortoise, 98. * Squirrels, enemies of the, 231; * flying, 231; * tree-loving rodents, 230. * Stickleback father defending the young, 65. * Sticklebacks and their nest, 65. * Sting-rays, 42. * Stomias, a deep-sea fish, 48. * Storks, migrations of, 151. * Struggle for existence, developing sympathy, 351; * improving the herbivora, 282. * Sturgeon entering a river, 31; * first appearance of the, 41; * head and mouth of, 32; * structure of, 32. * Sucking-fish or remora, 51. * Sun-fish with large air-bladder, 53. * Surinam toad, carrying young in hollows of the skin, 87. * Swallow, a darter among the perchers, 172. * Swans, range of wild, 142. * Swifts, darting birds, 167; * in East build nests with saliva, 167. * Sword-fish, Xiphias, 55. * Tadpole, life and changes of, 72–76; * of salamandra atra, 81; * summary of changes in the, 335. * Taguan or flying squirrel, 231. * Tail, jointed, of ancient land-bird, 130; * of minnow, 24; * homocercal and heterocercal, 30; * of bony fish, 45; * of sharks and sturgeon, 30. * Tailor bird’s nest, 173. * Tallegallus, mound-building birds, 158. * Tapirs, past and present range of, 264. * Tasmanian marsupials, 197. * Teeth as defences, 260; * in jaws of ancient birds, 130; * of American monkeys, 246; * of Old World monkeys, 248; * of ancient type of fish, 35, 38, 39; * of lamprey, 17, 19, 37; * of rodents and insect-eaters, 217; * of snake used in holding, 115; * of snake are its poison fangs, 119. * Tenrecs of Madagascar, 216. * Termites, ant-bear feeding on, 205. * Tern, black-winged, 144. * Terrapins or box-tortoises, 101. * Testudo Græca, 96. * Thresher-shark, 28. * Thrush, nest of the song-, 170. * Thuringian lizard, earliest reptile, 91. * Tiger, 287; * claws of the, 289; * man fighting the sabre-toothed, 333, 343; * range and habits of the, 292; * sabre-toothed, 290; * structure of the, 288. * Tiger wolf or Thylacinus, 197. * Tinamous, a group between running birds and ground birds, 156. * Toad, habits of the, 85. * Todies of America, 168. * Toe-thumbs in opossums, dormouse and monkey, 242. * Tongue of frog, 77; * of snake a harmless organ of touch, 112, 118, 119; * of the woodpecker, 164. * Torpedo-fish, 42. * Tortoise, back of a young, 99; * Greek, 96; * structure and habits of, 95–100. * Tortoises, gigantic land, 101; * mud and sea, 102. * Tortoise-shell, 97. * Toucans, climbing-birds, 165. * Tree-frogs, 86, 87. * Trilobites with the early fish, 37. * Trunk of the elephant, 277. * Tunny, a fish without air-bladder, 53. * Turkeys, scratching birds, 157. * Turnstones, wading birds, 148. * Turtles, 101, 102. * Tusks, as weapons, 260, 263; * of the elephant, 276; * wanting in early forms, 260. * Uneven-toed animals, origin of, 265. * Ungulata, or hoofed animals, 257. * Vampires in South America, 237. * Vegetable-feeders, see Herbivora. * Vertebrata, advantages of the, 7; * spinal cord of the, 9. * Viper, common English, 121; * killed by the buzzard, 120. * Viscacha of South America, 225. * Vultures, scavengers of the earth, 174. * Wading birds, a group of, 149. * Walking fish, 57. * Wallace, Mr. A. R., bitten by bats, 237; * on colugo, 232; * on mound-building birds, 159; * on orangutan, 252; * on separation of Australasia, 186. * Walrus, 294; * structure, home, and habits of the, 309. * Wart-hogs of Africa, 263. * Water-birds, the earliest known, 123; * structure of, 141. * Water-mole, 188. * Water-ouzel or dipper, 172. * Water-rat and water-shrew, 219. * Weasel, a small flesh-feeder, 280. * Weevers, spined fish, 58. * Whale, breathing apparatus of, 321; * skeleton of whalebone, 318; * suckling her young, 319; * ancient origin of, 303; * a warm-blooded mammal, 317; * kept warm by blubber, 320; * long life of, 331; * parasites on, 331. * Whalebone, nature of, 328. * Whiskers of tiger are feelers, 289. * White animal tints in winter, 347. * Wild duck, strokes of wing of, 134. * Wing, rapid strokes of a bird’s, 134; * structure of a bird’s, 127. * Wing-feathers, hooklets on, 133. * Wings of a bat, how formed, 233. * Wolf, affection of a, 286; * ancestor of the dog, 286; * dog-like form and teeth of, 283; * structure of, 284; * the only social tribe of carnivora, 286. * Wombat, 197; * a marsupial, 195. * Woodpecker, the great green, 163; * tongue of, 164. * Wood-pigeon on her nest, 160. * Woolly monkey and child, 247. * Worm, compared to the lancelet, 13. * Wren, common, nest of, 171. * Wryneck, 172. * Xiphodon, 210; * ancestor of the antlered animals, 213; * ancestor of ruminants, 261. * Yapock, 300.

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