754 INDEX. 



variability of the force of, 121; difference of force between the 

 social and other, 1?6, 143; utilized for new purposes, 651. 



Instrumental music of birds, 425, 430. 



Intellect, influence of, in natural selection in civilized society, 154. 



Intellectual faculties, their influence on natural selection in man, 

 144; probably perfected through natural selection, 146. 



Intelligence, Mr. H. Spencer on the dawn of, 75. 



Intemperance, no reproach among savages, 135; its destructive 

 ness. 155. 



Intoxication in monkeys, 7. 



Iphias glaucippe, 354. 



Iris, sexual difference in the color of the, in birds, 435, 483. 



Ischio- pubic muscle, 46. 



Ithnginu cruentas, number of spurs in. 413. 



lulus, tarsal suckers of the males of, 310. 



Jackals learning from dogs to 1 ark, 82. 



Jack snipe, coloration of the, 557. 



Jacquinot, on the number of species of man, 199. 



Jaeger, Dr., length of bones increased from carrying weights. 36; 

 on the difficulty of approaching herds of wild animals. 114; male 

 silver pheasant, rejected when his plumage was spoiled. 476. 



Jaguars, black, 616. 



Janson, E. W , on the proportions of the sexes in Tomicus nltosus, 

 286; on stridulant beetles, 342 



Japan, encouragement of licentiousness in, 52. 



Japanese, general beardlessness of the, 639; aversion of the, to 

 whiskers, 662. 



Jardine. Sir W.. on the Argus pheasant, 436. 457. 



Jarrold, Dr., on modifications of the skull induced by unnatural 

 position, 62. 



Jarves, Mr., on infanticide in the Sandwich Islands. 290. 



J a vans, relative height of the sexes of. 638; notions of female 

 beauty, 661. 



Jaw, influence of the muscles of the, upon the physiognomy of 

 the apes. 60. 



Jaws, smaller proportionately to the extremities. 37, influence of 

 food upon the si/e of, 37; diminution of. in man, 60; in man. re- 

 duced by correlation, 641. 



Jay, young of the, 548; Canada, young of the, 549. 



Jays, new mates found by, 463; distinguishing persons. 468. 



Jeffreys, J. rtwyn, on the form of the shell in the sexes of the 

 Gasteropoda, 297;" on the influence of light upon the colors of shells, 

 298. 



Jelly-fish, bright colors of some. 295. 



Jenner, Dr., on the voice of the rook, 426: on the finding of new 

 mates by magpies, 462: on retardation of the generative functions in 

 birds, 465. 



Jenyns, L., on the desertion of their young by swallows, 122; on 

 male birds singing after the proper season, 465. 



Jerdon. Dr., on birds dreaming, 84: on the pufrnarity of the male 

 bulbul, 409; on the pugnacity >f the mnlt- Ortygoriii* c/idaris, 412; 

 on the spurs of Gallvperdix, 413; on the habits of Lvbivatteilus, 414; 



