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.