ull 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.

_Ceroxylus laceratus_, imitates a moss-covered stick, 64.

CERTHIOLA, sexual colouring and nidification of, 244.

_Cethosia aeole_, 172;
_biblis_, 172.

CETONIADAE, how protected, 73;
similar colours of two sexes, 114.

CEYCOPSIS, 196.

_Charis melipona_, 96.

CHEMATOBIA, wintry colours of this genus, 62.

_Chlamys pilula_,