Part 44

Saturnia pavonia-minor, protective colouring of larva of, 63.

SATYRIDAE, probable means of protection of, 176.

SAUROPTERYGIA, 299.

SAVAGES, why they become extinct, 319; undeveloped intellect of, 339, 341; intellect of, compared with that of animals, 341, 343; protect their backs from rain, 346.

SCANSORIAL birds, nests of, 238.

SCAPHURA, 98.

SCISSIROSTRUM, 165.

SCOPULIPEDES, brush-legged bees, 91.

SCUDDER, Mr., on fossil insects, 301.

SCUTELLERIDAE, mimicked by Longicorns, 96.

Sesia bombiliformis, 90.

SESIIDAE, mimic Hymenoptera, 90.

SEXES, comparative importance of, in different classes of animals, 111; diverse habits of, 156.

SEXUAL SELECTION, 156; its normal action to develop colour in both sexes, 247; among birds, 283.

SIDGWICK, Mr. A., on protective colouring of moths, 62.

SIMOCYONIDAE, 300.

SITTA, sexual colouring and nidification of, 243.

SITTELLA, sexual colouring and nidification of, 243.

SNAKES, mimicry among, 101.

SONG of birds, instinctive or imitative, 220.

SPECIES, law of population of, 28; abundance or rarity of, dependent on the adaptation to conditions, 33; definition of, 141, 161; the range and constancy of, 143; extreme variation in, 163, 164.

SPEED of animals, limits of, 292.

Sphecia craboniforme, 90.

Sphecomorpha chalybea, 96.

SPHEGIDAE, mimicked by flies, 97.

SPIDERS, which mimic ants, 98; and flower buds, 99.

Spilosoma menthastri, 88.

STAINTON, Mr., on moths rejected by turkeys, 78, 88.