Part 46

Trochilium tipuliforme, 90.

TROGONIDAE, sexual colouring and nidification of, 241.

TROPICAL birds often green, 52.

TROPICS, most favourable to production of perfect adaptation among animals, 68; not favourable to growth of civilization, 318.

TROPIDORHYNCHUS mimicked by orioles, 104.

TRUTHFULNESS of some savages, 353; not to be explained on utilitarian hypothesis, 354.

TURDIDAE, sexual colouring and nidification of, 245.

TURNIX, 115, 251.

TYNDALL, Professor, on origin of consciousness, 361.

UPUPIDAE, sexual colouring and nidification of, 241.

USEFUL and useless variations, 34.

UTILITY, importance of the principle of, 47, 127.

VARIABILITY, simple, 144.

VARIATIONS, useful and useless, 34; laws of, 143, 266; as influenced by locality, 166; of size, 168; universality of, 287-291; are there limits to, 291; of domestic dogs, 293; of pigeons, 293.

VARIETIES, instability of, supposed to prove the permanent distinctness of species, 26; if superior will extirpate original species, 36; its reversion then impossible, 37; of domesticated animals may partially revert, 38, 40; inconvenience of using the term, 161.

VERTEBRATA, mimicry among, 99.

VOICE of man, not explained by natural selection, 350.

VOLUCELLA, species of mimic bees, 75, 98.

WALSH, Mr., on dimorphism, of Papilio turnus, 153.

WEAPONS and tools, how they affect man's progress, 314.

WEEVILS often resemble small lumps of earth, 58.

WEIR, Mr. Jenner, on a moth refused by birds, 89; on beetles refused by birds, 93; on caterpillars eaten and rejected by birds, 119.

WESTWOOD, Professor, objections to theory of mimicry, 108.

WHITE colour in domesticated and wild animals, 66.

WILD and domesticated animals, essential differences of, 38-41.

WILL really exerts force, 367; probably the primary source of force, 368.

WOOD, Mr. T. W., on orange-tip butterfly, 59.

WOODCOCKS and Snipes, protective colouring of, 53.