Birgus latro, habits of.

Birkbeck, Mr., on the finding of new mates by golden eagles.

Birthplace of man.

Births, numerical proportions of the sexes in, in animals and man; male and female, numerical proportion of, in England.

Bischoff, Prof., on the agreement between the brains of man and of the orang; figure of the embryo of the dog; on the convolutions of the brain in the human foetus; on the difference between the skulls of man and the quadrumana; resemblance between the ape's and man's.

Bishop, J., on the vocal organs of frogs; on the vocal organs of cervine birds; on the trachea of the Merganser.

Bison, American, co-operation of; mane of the male.

Bitterns, dwarf, coloration of the sexes of.

Biziura lobata, musky odour of the male; large size of male.

Blackbird, sexual differences in the; proportion of the sexes in the; acquisition of a song by; colour of the beak in the sexes of the; pairing with a thrush; colours and nidification of the; young of the; sexual difference in coloration of the.

Black-buck, Indian, sexual difference in the colour of the.

Blackcap, arrival of the male, before the female; young of the.

Black-cock, polygamous; proportion of the sexes in the; pugnacity and love-dance of the; call of the; moulting of the; duration of the courtship of the; and pheasant, hybrids of; sexual difference in coloration of the; crimson eye-cere of the.

Black-grouse, characters of young.

Blacklock, Dr., on music.

Blackwall, J., on the speaking of the magpie; on the desertion of their young by swallows; on the superior activity of male spiders; on the proportion of the sexes in spiders; on sexual variation of colour in spiders; on male spiders.

Bladder-nose Seal, hood of the.

Blaine, on the affections of dogs.

Blair, Dr., on the relative liability of Europeans to yellow fever.

Blake, C.C., on the jaw from La Naulette.

Blakiston, Captain, on the American snipe; on the dances of Tetrao phasianellus.

Blasius, Dr., on the species of European birds.

Bledius taurus, hornlike processes of male.

Bleeding, tendency to profuse.

Blenkiron, Mr., on sexual preference in horses.

Blennies, crest developed on the head of male, during the breeding season.

Blethisa multipunctata, stridulation of.

Bloch, on the proportions of the sexes in fishes.

Blood, arterial, red colour of.

Blood pheasant, number of spurs in.

Blow-fly, sounds made by.

Bluebreast, red-throated, sexual differences of the.

Blumenbach, on Man; on the large size of the nasal cavities in American aborigines; on the position of man; on the number of species of man.

Blyth, E., on the structure of the hand in the species of Hylobates; observations on Indian crows; on the development of the horns in the Koodoo and Eland antelopes; on the pugnacity of the males of Gallicrex cristatus; on the presence of spurs in the female Euplocamus erythrophthalmus; on the pugnacity of the amadavat; on the spoonbill; on the moulting of Anthus; on the moulting of bustards, plovers, and Gallus bankiva; on the Indian honey-buzzard; on sexual differences in the colour of the eyes of hornbills; on Oriolus melanocephalus; on Palaeornis javanicus; on the genus Ardetta; on the peregrine falcon; on young female birds acquiring male characters; on the immature plumage of birds; on representative species of birds; on the young of Turnix; on anomalous young of Lanius rufus and Colymbus glacialis; on the sexes and young of the sparrows; on dimorphism in some herons; on the ascertainment of the sex of nestling bullfinches by pulling out breast-feathers; on orioles breeding in immature plumage; on the sexes and young of Buphus and Anastomus; on the young of the blackcap and blackbird; on the young of the stonechat; on the white plumage of Anastomus; on the horns of Bovine animals; on the horns of Antilope bezoartica; on the mode of fighting of Ovis cycloceros; on the voice of the Gibbons; on the crest of the male wild goat; on the colours of Portax picta; on the colours of Antilope bezoartica; on the colour of the Axis deer; on sexual difference of colour in Hylobates hoolock; on the hog-deer; on the beard and whiskers in a monkey, becoming white with age.

Charles Darwin

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