i. 240;

common, said to be polygamous, i. 268; numerical proportion of the sexes in, i. 305.

RATS, enticed by essential oils, ii. 281.

RATIONALITY of birds, ii. 108.

RATTLE-SNAKES, difference of the sexes in the, ii. 29; said to use their rattles as a sexual call, ii. 30.

RAVEN, vocal organs of the, ii. 55; stealing bright objects, ii. 112; pied, of the Feroe Islands, ii. 120.

RAYS, prehensile organs of male, ii. 1.

RAZOR-BILL, young of the, ii. 217.

READE, Winwood, on the Guinea sheep, i. 289; non-development of horns in castrated male Guinea sheep, ii. 247; on the occurrence of a mane in an African ram, ii. 285; on the negroes' appreciation of the beauty of their women, ii. 344; on the admiration of negroes for a black skin, ii. 346; on the idea of beauty among negroes, ii. 350; on the Jollofs, ii. 357; on the marriage-customs of the negroes, ii. 374.

REASON, in animals, i. 46.

REDSTART, American, breeding in immature plumage, ii. 214.

REDSTARTS, new mates found by, ii. 105.

REDUVIDAE, stridulation of, i. 350.

REED-BUNTING, head-feathers of the male, ii. 95; attacked by a bullfinch, ii. 111.

REEFS, fishes frequenting, ii. 17.

REGENERATION, partial, of lost parts in man, i. 13.

REGENT-BIRD, ii. 112.

REINDEER, antlers of, with numerous points, ii. 252; sexual preferences shown by, ii. 273; horns of the, i. 288; winter change of the, ii. 299; battles of, ii. 240; horns of the female, ii. 243.

RELATIONSHIP, terms of, ii. 360.

RELIGION, deficiency of, among certain races, i. 65; psychical elements of, i. 68.

REMORSE, i. 91; deficiency of, among savages, i. 164.

RENGGER, on the diseases of _Cebus Azarae_, i. 11; on maternal affection in a _Cebus_, i. 40; revenge taken by monkeys, i. 40; on the reasoning powers of American monkeys, i. 47; on the use of stones by monkeys for cracking hard nuts, i. 51; on the sounds uttered by _Cebus Azarae_, i. 54; on the signal-cries of monkeys, i. 57; on the diversity of the mental faculties of monkeys, i. 110; on the Payaguas Indians, i. 117; on the inferiority of Europeans to savages in their senses, i. 118; on the polygamous habits of _Mycetes caraya_, i. 266; on the voice of the howling monkeys, ii. 277; on the odour of _Cervus campestris_, ii. 279; on the beards of _Mycetes caraya_ and _Pithecia Satanas_, ii. 283; on the colours of _Felis mitis_, ii. 287; on the colours of _Cervus paludosus_, ii. 290; on sexual differences of colour in _Mycetes_, ii. 291; on the colour of the infant Guaranys, ii. 318; on the early maturity of the female of _Cebus azarae_, ii. 318; on the beards of the Guaranys, ii. 322, 323; on the emotional notes employed by monkeys, ii. 336; on American polygamous monkeys, ii. 362.

REPRESENTATIVE species, of birds, ii. 190, 191.

REPRODUCTION, unity of phenomena of, throughout the mammalia, i. 13; period of, in birds, ii. 214.

REPRODUCTIVE system, rudimentary structures in the, i. 30; accessory parts of, i. 207.

REPTILES, ii. 28.

REPTILES and birds, alliance of, i. 213.

RESEMBLANCES, small, between man and the apes, i. 191.

RETRIEVERS, exercise of reasoning faculties by, i. 48.

REVENGE, manifested by animals, i. 40.

REVERSION, i. 122; perhaps the cause of some bad dispositions, i. 173.

_Rhagium_, difference of colour in the sexes of a species of, i. 367.

_Ramphastos carinatus_, ii. 227.

RHINOCEROS, nakedness of, i. 148; horns of, ii. 247; horns of, used defensively, ii. 263; attacking white or grey horses, ii. 295.

_Rhynchaea_, sexes and young of, ii. 202.

_Rhynchaea australis_, ii. 203.

_Rhynchaea bengalensis_, ii. 203.

_Rhynchaea capensis_, ii. 202.

RHYTHM, perception of, by animals, ii. 333.

RICHARD, M., on rudimentary muscles in man, i. 19.

RICHARDSON, Sir J., on the pairing of _Tetrao umbellus_, ii. 49; on _Tetrao urophasianus_, ii. 58; on the drumming of grouse, ii. 63; on the dances of _Tetrao phasianellus_, ii. 69; on assemblages of grouse, ii. 101; on the battles of male deer, ii. 240; on the reindeer, ii. 244; on the horns of the musk-ox, ii. 247; on antlers of the reindeer with numerous points, ii. 252; on the moose, ii. 259.

RICHARDSON, on the Scotch deerhound, ii. 261.

RICHTER, Jean Paul, on imagination, i. 45.

RIEDEL, on profligate female pigeons, ii. 119.

RING-OUZEL, colours and nidification of the, ii. 170.

RIPA, Father, on the difficulty of distinguishing the races of the Chinese, i. 215.

RIVALRY, in singing, between male birds, ii. 53.

RIVER-HOG, African, tusks and knobs of the, ii. 266.

RIVERS, analogy of, to islands, i. 204.

ROACH, brightness of male during breeding-season, ii. 13.

ROBBERY, of strangers, considered honourable, i. 94.

ROBERTSON, Mr., remarks on the development of the horns in the roebuck and red-deer, i. 288.

ROBIN, pugnacity of the male, ii. 40; autumn song of the, ii. 54; female, singing of the, ii. 54; attacking other birds with red in their plumage, ii. 111; young of the, ii. 208.

ROBINET, on the difference of size of the male and female cocoons of the silk-moth, i. 346.

RODENTS, uterus in the, i. 123; absence of secondary sexual characters in, i. 268; sexual differences in the colours of, ii. 286.

ROE, winter change of the, ii. 299.

ROLLE, F., on the origin of man, i. 4; on a change in German families settled in Georgia, i. 246.

ROLLER, ii. 56.

ROMANS, ancient, gladiatorial exhibitions of the, i. 101.

ROOK, voice of the, ii. 61.

ROESSLER, Dr., on the resemblance of the lower surface of butterflies to the bark of trees, i. 392.

ROSTRUM, sexual difference in the length of, in some weevils, i. 255.

RUDIMENTARY organs, i. 17; origin of, i. 32.

RUDIMENTS, presence of, in languages, i. 60.

RUDOLPH, on the want of connexion between climate and the colour of the skin, i. 241.

RUFF, supposed to be polygamous, i. 270; proportion of the sexes in the, i. 306; pugnacity of the, ii. 41, 48; double moult in, ii. 81, 84; duration of dances of, ii. 100; attraction of the, to bright objects, ii. 111.

RUMINANTS, male, disappearance of canine teeth in, i. 144, ii. 325; generally polygamous, i. 266; analogy of Lamellicorn beetles to, i. 373; suborbital pits of, ii. 280; sexual differences of colour in, ii. 287.

_Rupicola crocea_, display of plumage by the male, ii. 87.

RUEPPELL, on canine teeth in deer and antelopes, ii. 258.

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

_Ruticilla_, ii. 180.

RUETIMEYER, Prof., on the physiognomy of the apes, i. 149; on the sexual differences of monkeys, ii. 323.

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

S.

SACHS, Prof., on the behaviour of the male and female elements in fertilisation, i. 274.

SACRIFICES, Human, i. 182.

SAGITTAL crest in male apes and Australians, ii. 319.

SAHARA, birds of the, ii. 172; animal inhabitants of the, ii. 224.

SAILORS, growth of, delayed by conditions of life, i. 114; long-sighted, i. 118.

SAILORS and soldiers, difference in the proportions of, i. 116.

ST. JOHN, Mr., on the attachment of mated birds, ii. 108.

ST. KILDA, beards of the inhabitants of, ii. 321.

_Salmo eriox_, and _S. umbla_, colouring of the male, during the breeding season, ii. 14.

_Salmo lycaodon_, ii. 4.

_Salmo salar_, ii. 4.

SALMON, leaping out of fresh water, i. 83; male, ready to breed before the female, i. 260; proportion of the sexes in, i. 308; male, pugnacity of the, ii. 3; male, characters of, during the breeding season, ii. 3, 14; spawning of the, ii. 19; breeding of immature male, ii. 215.

SALVIN, O., on the Humming-birds, i. 269, ii. 168; on the numerical proportion of the sexes in Humming-birds, i. 307, ii. 221; on _Chamaepetes_ and _Penelope_, ii. 64; on _Selasphorus platycercus_, ii. 65; on _Pipra deliciosa_, ii. 66; on _Chasmorhynchus_, ii. 79.

SAMOA Islands, beardlessness of the natives of, ii. 322, 349.

SAND-SKIPPER, i. 334.

SANDWICH Islands, variation in the skulls of the natives of the,