Part 43

PIERIS, females only imitating Heliconidae, 112.

Pieris coronis, 172; eperia, 172.

Pieris pyrrha, 113.

PICIDAE, sexual colouring and nidification of, 242.

PIPRIDAE, sexual colouring and nidification of, 245.

PITTIDAE, 253.

Pliocerus equalis, 101; P. elapoides, P. euryzonus, 102.

Paeciloderma terminale, 93.

POLARITY, Forbes' theory of, 17, 45.

POLYMORPHISM, 145; illustration of, 157.

POPULATION of species, law of, 28; does not permanently increase, 29; not determined by abundance of offspring, 29; checks to, 30; difference in the case of cats and rabbits explained, 32.

PREVISION, a case of, 122.

PRIONITURUS, 196.

PROTECTION, various modes in which animals obtain it, 69-71, 258; greater need of, in female insects and birds, 113.

PROTECTIVE colouring, theory of, 65.

PSITTACI (Parrots), sexual colouring and nidification of, 242.

PTEROSAURIA, 298.

PTYCHODERES, 94.

RACES, or subspecies, 160; of man, origin of, 319.

REDBREAST and woodpigeon, protective colouring of, 53, 54.

REPRESENTATIVE groups, 9; of Trogons, butterflies, &c., 12.

REPTILES, protective colouring of, 54.

RHAMPHASTIDAE, sexual colouring and nidification of, 242.

RHINOCEROS, 299.

RIVER system, as illustrating self-adaptation, 276.

ROSES, Mr. Baker on varieties of, 165.

RUDIMENTARY organs, 23.

SALVIN, Mr. Osbert, on a case of bird mimicry, 107.