754 INDEX. 



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

 social and other, l!;^,6, 148; utilized for new purposes, 651. 



Instruniental music of birds, 425, 480. 



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



Intellectual faculties, their intiuence on natural selection in man, 

 144; prol)ably perfected through natural selection, 140. 



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



Intenii)erance, no reproach among savages, 135; its destructive- 

 ness, 155. 



Intoxication in monkeys, 7. 



Iphias f/laucippe, 354. 



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



Ischio- pubic muscle, 46. 



Ithaginis cruentas, number of spurs in, 413. 



lulus, tarsal suckers of the males of, 310. 



Jackals learning from dogs to lark, 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 vUlosus, 

 286; on stridulant beetles, 342. 



Japan, encouragement of licentiousness in, 52. 



Japanese, general beardlessness of the, 639; aversion of tL.e, 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 size 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. tiwyn, 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. 



Jnner, 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 pugnacity of the male 

 bulbul, 409; on the pugnacity of the male Ortygornis guldris, 412; 

 on the spurs of Oalloperdix, 413; on the habits of LobivaneUus, 414; 



