INDEX, 797 



Wren, 539; young of the, 539, 548. 



Wright, C A., on the young of Orocetes and Petrocincla, 554; 

 Wright, Chauncey, great brain-power requisite for language 54; on 

 correlative acquisition, 651 ; on the enlargement of the brain in 

 man, 697; Wright, Mr., on the Scotch deerhound, 689; on sexual 

 preference in dogs, 597; on the rejection of a horse by a mare, 598; 

 Wright, W., von, on the protective plumage of the Ptarmigan, 443, 



Writing, 163. 



Wyman, Prof., on the prolongation of the coccyx in the human 

 embryo, 10; on the condition of the great toe in the human 

 embryo, 12; on the occurrence of the supra-con dyloid foramen in the 

 humerus of man, 24; on variation in the skulls of the natives of the 

 Sandwich Islands, 29; on the hatching of the eggs in the mouths 

 and branchial cavities of male fishes, 185, 391. 



Xenarchus, on the Cicadae, 319. 



Xenophon, selection in mankind advocated by, 32. 



Xenorhyiichus, sexual difference in the color of the eyes in, 483. 



Xiphophorus Helleni, peculiar analfin of the male, 382. 



Xylucopn, difference of the sexes in, 331. 



Yarrell, W., on the habits of the Oyprinidae, 282; on Raia clavata, 

 375; on the characters of the male salmon during the breeding- 

 season, 377, 386; on the characters of the rays, 380; on the gemmeous 

 dragonet, 381; on colors of the salmon, 386; on the spawning of the 

 salmon, 390; on the incubation of the Lophobranchii, 392; on rivalry 

 in song-birds, 419; on the trachea of the swan, 425; on the moulting 

 of the Anatidae, 446; on the young of the waders, 553. 



Yellow fever, immunity of negroes and mulattoes from, 220. 



Youatt, Mr., on the development of the horns in cattle, 266. 



Yura-caras, their notions of beauty, 661. 



Zebra, rejection of an ass by a female, 617; stripes of the, 623. 



Zebus, humps of, 608. 



Zigzags, prevalence of, as ornaments, 204. 



Zincke, Mr., on European emigration to America, 161. 



Zovtoca viviparn, sexual difference in the color of, 405. 



Zouteveen, Dr., polydactylism, 42; proportion of sexes at Cape of 

 Good Hope, 275; spiders attracted by music, 309; on sounds pro- 

 duced by fish, 394. 



Zygaenidae, coloration of the, 356. 



THE "BtSD, 



