INDEX. 723 



migratory, arrival of the male before the female, 241; apparent rela- 

 tion between polygamy and marked sexual differences in, 248; 

 monogamous, becoming polygamous under domestication, 249; 

 eagerness of male in pursuit of the female, 250; wild, numerical 

 proportion of the sexes in, 280; secondary sexual characters of, 407; 

 difference of size in the sexes of, 411; fights of male, witnessed by 

 females, 414; display of male, to captivate the females, 416; close 

 attention of, to the songs of others, 418; acquiring the song of their 

 foster parents, 420; Lrilliant, rarely good songsters, 421; love-antics 

 and dances of, 431; coloration of, 438 et seq.; moulting of, 442 et seq.; 

 unpaired, 462; male, singing out of season, 465; mutual affection of, 

 466; in confinement, distinguish persons, 467; hybrid, production of, 

 470; Albino, 476; European, number of species of, 479; variability 

 of, 479; geographical distribution of coloring, 480; gradation of 

 secondary sexual characters in, 488; obscurely colored, building con- 

 cealed nests, 516; young female, acquiring male characters, 525; 

 breeding in immature plumage, 551; moulting of, 551; aquatic, fre- 

 quency of white plumage in, 561; vocal courtship of, 646; naked 

 skin of the head and neck in, 686. 



Birgus tatro, habits of, 305. 



Birkbeck, Mr., on the finding of new mates by golden eagles, 463. 



Birthplace of man, 176. 



Births, numerical proportions of the sexes in, in animals and 

 man, 243, 244; male and female, numerical proportion of, in England, 

 274. 



Bischoff, Prof., on the agreement between the brains of man and 

 of the orang, 6; figure of the embryo of the dog, 11; on the convo- 

 lutions of the brain in the human fetus, 10; on the difference 

 between the skulls of man and the quadruinana, 170; resemblance 

 between the ape's and man's, 227. 



Bishop, J., on the vocal organs of frogs, 397; on the vocal organs 

 of corvine birds, 421; on the trachea of the Merganser, 425. 



Bison, American, co-operation of, 115; mane of the male, 594. 



Bitterns, dwarf, coloration of the sexes of, 524. 



Biziura lobata, musky odor of the male, 407; large size of male, 

 411. 



Blackbird, sexual differences in the, 248; proportion of the sexes 

 in the, 281; acquisition of a song by, 421; color of the beak in the 

 sexes of the, 435, 559; pairing with a thrush, 470; colors and nidifi- 

 cation of the, 517; young of the, 554, 555; sexual difference in colora- 

 tion of the, 559. 



Black-buck, Indian, sexual difference in the color of the, 612. 



Blackcap, arrival of the male, before the female, 240; young of 

 the, 554. 



Black-cock, polygamous, 248; proportion of the sexes in the, 279; 

 pugnacity and love-dance of the, 412; call of the, 425 ; moulting of 

 the, 444; duration of the courtship of the, 460 ; and pheasant, 

 hybrids of, 125; sexual difference in coloration of the, 559; crimson 

 eye-cere of the, 559. 



Black-grouse, characters of young, 530, 537. 



Blacklock, Dr., on music, 653. 



Blackwall, J., on the speaking of the magpie, 101; on the deser- 

 tion of their young by swallows, 122; on the superior activity of 



