ARGYLL, Duke of, on colours of Woodcock, 53; on mind in nature, 265; criticism on Darwin's works, 269; on humming birds 282; on creation by birth, 287. ASILUS, 97. ASPECTS of nature as influencing man's development, 317. BABIRUSA, 196. BALANCE in nature, 42. BARRINGTON, Hon. Daines, on song of birds, 220. BASILORNIS, 196. BATES, Mr., first adopted the word "mimicry," 75; his observations on Leptalis and Heliconidae, 82; his paper explaining the theory of mimicry, 83; objections to his theory, 108; on variation, 165; on recent immigration of Amazonian Indians, 214. BAYMA, Mr., on "Molecular Mechanics," 363, 364. BEAUTY in nature, 282; not universal, 284; of flowers useful to them, 285; not given for its own sake, 285. BIRDS, possible rapid increase of, 29; numbers that die annually, 30; mimicry among, 103; dull colour of females, 114; nidification as affecting colour of females, 116; refusing the gooseberry caterpillar, 119; the highest in rank and organization, 137; dimorphism in, 155; why peculiar nest built by each species, 215-219; build more perfect nests as they grow older, 224, 227; alter and improve their nests, 226; sexual differences of colour in, 239. _Bombus hortorum_, 90. _Bombycilla, garrula_, colours and nidification of, 255. BOMBYLIUS, 98. BRAIN of the savage but slightly less than that of civilized man, 336; size of, an important element of mental power, 335; of savage races larger than their needs require, 338, 343; of man and of anthropoid apes compared, 338. BROCA, Professor Paul, on the fine crania of the cave men, 337. _Bryophila glandifera_ and _B. perla_ protectively coloured, 63. BUCEROTIDAE, sexual colouring and nidification of, 241. BUCCONIDAE, sexual colouring and nidification of, 241. BUFF-TIP moth, resembles a broken stick, 62. BUILDINGS of various races do not change, 213. BUPRESTIDAE, resembling bird's dung, 57; similar colours in two sexes, 114. BUTTERFLIES, value of, in studying "natural selection," 131; varieties of, in Sardinia and Isle of Man, 178. _CACIA anthriboides_, 94. _Callizona acesta_, protective colouring of, 59. CALORNIS, 239. CAPITONIDAE, sexual colouring and nidification of, 241. _Capnolymma stygium_, 94. CARABIDAE, special protection among, 72; similar colouring of two sexes, 114. CASSIDAE, resemble dew drops, 58. CATERPILLARS, mimicking a poisonous snake, 99; gaudy colours of, 117; various modes of protection of, 118; gooseberry caterpillar, 119; Mr. Jenner Weir's observations on, 119; Mr. A. G. Butler's observations on, 121. CELEBES, local modifications of form in, 170; probable cause of these, 176; remarkable zoological peculiarities of, 195-199. CENTROPUS, sexual colouring and nidification of, 242. _Cephalodonta spinipes_, 92.