50U 



INDEX. 



Thrush, nest of, $59. 



Thuret, M., on crossed fuci, 269. 



Thwaites, Mr., on acclimatization, 

 126. 



Thylacinus, 414. 



Tierra del Fuego, dogs of, 233. 

 plants of, 478. 



Timber-drift, 361. 



Time, lapse of, 295. 

 by itself not causing modification, 

 90. 



Titmouse, 158. 



Toads on islands, 388. 



Tobacco, crossed varieties of, 286. 



Tomes, Mr., on the distribution of 

 bats, 389. 



Transitions in varieties rare, 150. 



Traquair, Dr., on flat- fish, 209. 



Trautschold, on intermediate vari- 

 eties, 305. 



Trees on islands belong to peculiar 

 orders, 387. 

 with separated sexes, 87. 



Trifolium pratense, 64, 83. 

 incarnatum, 83. 



Trigonia, 329. 



Trilobites, 317. 



sudden extinction of, S29. 



Trimen, Mr., on imitating insects, 

 417. 



Trimorphism in plants, 39, 279. 



Troglodytes, 259. 



Tuco-tuco-blind, 123. 



Tumbler pigeons, habits of, heredi- 

 tary, 232. 



Tumbler, young of, 434. 



Turkey-cock, tuft of hair on breast, 

 78. 

 naked skin on head, 177. 

 young of, instinctively wild, 233. 



Turnip and cabbage, analogous 

 variations of, 140. 



Type, unity of, 186. 



Types, succession of, in same areas, 

 344. 



Typotherium, 335. 



Udders, enlarged by use, 10. 



rudimentary, 441. 

 Ulex, young leaves of, 429. 

 Umbelliferoe, flowers and seeds of, 

 130. 



outer and inner florets of, 193. 

 Unity of type, 186. 

 Uria lacrymans, 80. 



Use, effects of, under domestical 



tion, 10. 

 effects of, in a state of nature, 



121. 

 Utility, how far important in the 



construction of each part, 178. 



Valenciennes, on fresh-water fish, 



381. 

 Variability of mongrels and hy 



brids, 287. 

 Variation, under domestication, 7. 

 caused by reproductive system 

 being affected by conditions ot 

 life, 8. 

 under nature, 37. 

 laws of, 119. 

 correlated, 10, 128, 178. 

 Variations appear at correspond- 

 ing ages, 12, 75. 

 analogous in distinct species, 139. 

 Varieties, natural, 35. 

 struggle between, 66. 

 domestic, extinction of, 95. 

 transitional, rarity of, 150. 

 when crossed, fertile, 283. 

 Varieties, when crossed, sterile. 

 284. 

 classification of, 411. 

 Verbascum, sterility of, 264. 



varieties of, crossed, 285. 

 Verlot, M., on double stocks, 254. 

 Verneuil, M. de, on the succession 



of species, 332. 

 Vibracula of the Polyzoa, 215. 

 Viola, small imperfect flowers of, 

 192. 

 tricolor, 64. 

 Virchow, on the structure of the 



crystalline lens, 163. 

 Virginia, pigs of, 74. 

 Volcanic islands, denudation of 



297. 

 Vulture, naked skin on head, 177. 



Wading-birds, 383. 



Wagner, Dr., on Cecidomyia, 428. 



Wagner, Moritz, on the importance 

 of isolation, 90. 



Wallace, Mr., on origin of spe- 

 cies, 1. 

 on the limit of variation under 



domestication, 33. 

 on dimorphic lepidoptera, 4$ 

 257. 



