738 INDEX, 



84; diverging when drawing sledges over thin ice, 85; exercise of 

 reasoning faculties by, 88; domestic, progress of, in moral qualities, 

 90; distinct tones uttered by, 95; parallelism between his affection 

 for his master and religious feeling, 108; sociability of the, IIB; 

 sympathy of, with a sick cat, 116; sympathy of, with his master, 

 116 ; their possession of conscience, 117; possible use of the hair 

 on the fore legs of the, 172; races of the, 201; numerical proportion 

 of male and female births in, 278; sexual affection between individ- 

 uals of, 215; howling at certain notes, 649; rolling in carrion, 605. 



Dolichocephalic structure, possible cause of, 63. 



Dolphins, nakedness of, 63. 



Domestic animals, races of, 201 ; change of breeds of, 680. 



Domestication, influence of, in removing the sterility of hybrids, 

 196. 



D'Orbigny, A., on the influence of dampness and dryness on the 

 color of the skin, 220; on the Yuracaras, 661. 



Dotterel, 544. 



Doubleday, E., on sexual differences in the wings of butterflies, 

 314; H., on the porportion of the sexes in the smaller moths, 284; 

 males of Lasiocampa quercus and on the attraction of the Satumia 

 carpini by the female, 284 ; on the proportion of the sexes in the 

 Lepidoptera, 284; on the ticking of Anobium tesselatum, 347; on the 

 structure of Ageronia ferania, 349; on white butterflies alighting 

 upon paper, 359. 



Douglas, J. W-, on the sexual differences of the Hemiptera, 318; 

 colors of British Homoptera, 318. 



Down, of birds, 442. 



Draco, gular appendages of, 402. 



Dragonet, Gemmeous, 381. 



Dragon-flies, caudal appendages of male, 313 ; relative size of the 

 sexes of, 316; difference in the sexes of, 328; want of pugnacity by 

 the male, 330. 



Drake, breeding plumage of the, 446. 



Dreams, 84; possible source of the belief in spiritual agencies, 107. 



Drill, sexual difference of 6olor in the, 614. 



Drommus irroratus, 545. 



Dromolcea, Saharan species of, 519. 



Drongo shrike, 524. 



Drongos, racket-shaped feathers in the tails of, 436, 445. 



Dryness of climate, supposed influence of, on the color of tin' 

 skin, 220. 



Drp(>])it?icus, 177. 



Duck, harlequin, age of mature plumage in the, 552; breeding in 

 immature ])lumage, 552; long-tailed, preference of male, for certain 

 females, 478; pintail, pairing with a widgeon, 471; voice of the, 425; 

 pairing with a shield-drake, 471 ; immature plumage of the, 5H2; 

 wild, sexual differences in the, 248; speculum and male characters of, 

 267; pairing with a pintail drake, 471. 



Ducks, wild, becoming polygamous under partial domestication, 

 249; dogs and cats recognized by, 468. 



Dufosse, Dr., sounds produced by fish, 393. 



Dugong, nakedness of, 63; tusks of, 572. 



Dujardin, on the relative size of the cerebral ganglia in ipsects, 61, 



