i. 210;

changes of plumage in, i. 281; transmission of sexual peculiarities in, i. 283; changing colour after several moultings, i. 294; numerical proportion of the sexes in, i. 306; cooing of, ii. 60; variations in plumage of, ii. 74; display of plumage by male, ii. 96; local memory of, ii. 109; antipathy of female, to certain males, ii. 118; pairing of, ii. 118, 119; profligate male and female, ii. 119; wing-bars and tail-feathers of, ii. 131; supposititious breed of, ii. 155; pouter and carrier, peculiarities of predominant in males, ii. 158; nidification of, ii. 168; immature plumage of the, ii. 188; Australian, ii. 175; Belgian, with black-streaked males, i. 285, 293; ii. 157.

PIGS, origin of the improved breeds of, i. 230; numerical proportion of the sexes in, i. 305; stripes of young, ii. 184, 303; sexual preference shown by, ii. 273.

PIKE, American, brilliant colours of the male, during the breeding season, ii. 14.

PIKE, male, devoured by females, i. 308.

PIKE, L. O., on the psychical elements of religion, i. 68.

_Pimelia striata_, sounds produced by the female, i. 385.

PINTAIL Drake, plumage of, ii. 84; pairing with a wild duck, ii. 115.

PINTAIL Duck, pairing with a Wigeon, ii. 114.

PIPE-FISH, filamentous, ii. 18; marsupial receptacles of the male, ii. 21.

PIPITS, moulting of the, ii. 83.

_Pipra_, modified secondary wing-feathers of male, ii. 65.

_Pipra deliciosa_, ii. 65, 66.

_Pirates stridulus_, stridulation of, i. 350.

_Pithecia leucocephala_, sexual differences of colour in, ii. 290.

_Pithecia Satanas_, beard of, ii. 283, 284, 285; resemblance of, to a negro, ii. 381.

PITS, suborbital, of Ruminants, ii. 280.

PITTIDAE, nidification of, ii. 167.

PLACENTATA, i. 202.

PLAGIOSTOMOUS fishes, ii. 1.

PLAIN-WANDERER, Australian, ii. 201.

_Planariae_, bright colours of some, i. 322.

PLANTAIN-EATERS, colours and nidification of the, ii. 171; both sexes of, equally brilliant, ii. 177.

PLANTS, cultivated, more fertile than wild, i. 132; Naegeli, on natural selection in, i. 152; male flowers of, mature before the female, i. 260; phenomena of fertilisation in, i. 273; relation between number and size of seeds in, i. 317.

_Platalea_, ii. 60; change of plumage in, ii. 179.

_Platyblemnus_, i. 361.

_Platycercus_, young of, ii. 209.

_Platyphyllum concavum_, i. 352, 356.

PLATYRRHINE monkeys, i. 196.

PLATYSMA _myoides_, i. 19.

_Plecostomus_, head-tentacles of the male of a species of, ii. 10.

_Plecostomus barbatus_, peculiar beard of the male, ii. 10.

_Plectropterus gambensis_, spurred wings of, ii. 46.

_Ploceus_, ii. 54.

PLOVERS, wing-spurs of, ii. 48; double moult in, ii. 83.

PLUMAGE, changes of, inheritance of, by fowls, i. 281; tendency to analogous variation in, ii. 74; display of, by male birds, ii. 86, 96; changes of, in relation to season, ii. 180; immature, of birds, ii. 183, 187; colour of, in relation to protection, ii. 223.

PLUMES on the head in birds, difference of, in the sexes, ii. 164.

_Pneumora_, structure of, i. 357.

_Podica_, sexual difference in the colour of the irides of, ii. 128.

POEPPIG, on the contact of civilised and savage races, i. 239.

POISON, avoidance of, by animals, i. 49.

POISONOUS fruits and herbs avoided by animals, i. 36.

POISONS, immunity from, correlated with colour, i. 242.

POLISH fowls, origin of the crest in, i. 284.

POLLEN and van Dam, on the colours of _Lemur macaco_, ii. 290.

POLYANDRY, ii. 365; in certain cyprinidae, i. 309; among the elateridae, i. 313.

POLYDACTYLISM in man, i. 125.

POLYGAMY, influence of, upon sexual selection, i. 265; superinduced by domestication, i. 270; supposed increase of female births by, i. 303; in the stickleback, ii. 2.

POLYGENISTS, i. 228.

POLYNESIA, prevalence of infanticide in, ii. 364.

POLYNESIANS, aversion of, to hairs on the face, ii. 349; wide geographical range of, i. 112; difference of stature among the, i. 115; crosses of, i. 225; variability of, i. 225; heterogeneity of the, i. 241.

_Polyplectron_, display of plumage by the male, i. 89; number of spurs in, ii. 46; gradation of characters in, ii. 137; female of, ii. 194.

_Polyplectron chinquis_, ii. 90, 138, 139.

_Polyplectron Hardwickii_, ii. 138, 139.

_Polyplectron malaccense_, ii. 139, 140.

_Polyplectron Napoleonis_, ii. 138, 140.

POLYZOA, i. 324.

_Pontoporeia affinis_, i. 329.

PORCUPINE, mute, except in the rutting season, ii. 274.

PORES, excretory, numerical relation of, to the hairs in sheep, i. 248.

_Porpitae_, bright colours of some, i. 322.

_Portax picta_, dorsal crest and throat-tuft of, ii. 282; sexual differences of colour in, ii. 287, 299.

_Portunus puber_, pugnacity of, i. 332.

_Potamochoerus penicillatus_, tusks and facial knobs of the, ii. 266.

POUCHET, G., on the ratio of instinct and intelligence, i. 37; on the instincts of ants, i. 187; on the caves of Abou-Simbel, i. 217; on the immunity of negroes from yellow fever, i. 243.

POUTER pigeon, late development of the large crop in, i. 293.

POWER, Dr., on the different colours of the sexes in a species of _Squilla_, i. 335.

POWYS, Mr., on the habits of the chaffinch in Corfu, i. 307.

PRE-EMINENCE of man, i. 137.

PREFERENCE for males by female birds, ii. 113, 122; shown by mammals, in pairing, ii. 268.

PREHENSILE organs, i. 256.

_Presbytis entellus_, fighting of the male, ii. 324.

PREYER, Dr., on supernumerary mammae in women, i. 125.

PRICHARD, on the difference of stature among the Polynesians, i. 115; on the connection between the breadth of the skull in the Mongolians and the perfection of their senses, i. 119; on the capacity of British skulls of different ages, i. 146; on the flattened heads of the Colombian savages, ii. 340; on Siamese notions of beauty, ii. 345; on the beardlessness of the Siamese, ii. 349; on the deformation of the head among American tribes and the natives of Arakhan, ii. 352.

PRIMARY sexual organs, i. 254.

PRIMATES, i. 190; sexual differences of colour in, ii. 290.

PRIMOGENITURE, evils of, i. 170.

_Primula_, relation between number and size of seeds in, i. 317.

PRIONIDAE, difference of the sexes in colour, i. 367.

_Proctotretus multimaculatus_, ii. 26, 37.

_Proctotretus tenuis_, sexual difference in the colour of, ii. 37.

PROFLIGACY, i. 173.

PROGENITORS, early, of man, i. 206.

PROGRESS, not the normal rule in human society, i. 166; elements of, i. 177.

PRONG-HORN, horns of, i. 289.

PROPORTIONS, difference of, in distinct races, i. 216.

PROTECTIVE colouring in butterflies, i. 392; in lizards, ii. 37; in birds, ii. 197, 223; in mammals, ii. 298, 299.

PROTECTIVE nature of the dull colouring of female Lepidoptera, i. 403, 405, 414.

PROTECTIVE resemblances in fishes, ii. 18.

PROTOZOA, absence of secondary sexual characters in, i. 321.

PRUNER-BEY, on the occurrence of the supra-condyloid foramen in the humerus of man, i. 29; on the colour of negro infants, ii. 318.

PRUSSIA, numerical proportion of male and female births in, i. 301.

_Psocus_, proportions of the sexes in, i. 314.

PTARMIGAN, monogamous, i. 269; summer and winter plumage of the, ii. 81, 83; nuptial assemblages of, ii. 101; triple moult of the, ii. 181; protective coloration of, ii. 198.

PUFF-BIRDS, colours and nidification of the, ii. 171.

PUGNACITY of fine-plumaged male birds, ii. 93.

PUMAS, stripes of young, ii. 183.

PUPPIES learning from cats to clean their faces, i. 44.

_Pycnonotus haemorrhous_, pugnacity of the male, ii. 41; display of under tail coverts by the male, ii. 96.

_Pyranga aestiva_, male aiding in incubation, ii. 167.

_Pyrodes_, difference of the sexes in colour, i. 367.

Q.

QUADRUMANA, hands of, i. 139; differences between man and the, i. 190; dependence of, on climate, i. 218; sexual differences of colour in, ii. 290; ornamental characters of, ii. 306; analogy of sexual differences of, with those of man, ii. 318; fighting of males for the females, ii. 324; monogamous habits of, ii. 361; beards of the, ii. 378.

QUAIN, R., on the variation of the muscles in man, i. 109.

QUATREFAGES, A. de, on the occurrence of a rudimentary tail in man,