INDEX 



463 



Strata, thickness of, in Britain, 



254. 

 Stripes on horses, 148. 

 Structure, degrees of utility of, 181. 

 Struggle for existence, 58. 

 Succession, geological, 280. 

 Succession of types in same areas, 



304. 

 Swallow, one specie? supplanting 



&:i other, 70. 

 Swim-bladder, 171. 

 System, natural, 372. 



Tail of giraffe, 175. 



of aquatic animals, 176. 



rudimentary, 408. 



Tarsi deficient, 122. 



Tausch on umbelliferous flowers, 



132. 

 Teeth and hair correlated, 131. 



embryonic, traces of, in birds, 



405. 



rudimentary, in embryonic 



calf, 405, 432. 



Tegetmeier, Mr., on cells of bees, 



204, 210. 

 Temminck on distribution aiding 



classification, 377. 

 Thouin on grafts, 235. 

 Thrush, aquatic species of, 166. 

 mocking, of the Galapagos, 



861. 



395. 



young of, spotted, 



nest of, 218. 



Thuret, M., on crossed fuci, 232. 

 Thwaites, Mr. , on acclimatisation, 



127. 

 Tierra del Fuego, doss of, 193. 



plants of, 339, 342. 



Timber-drift. 324. 

 Time, lapse of, 253. 

 Titmouse, 165. 



Toads on islands, 353. 



Tobacco, crossed varieties of, 243. 



Tomes, Mr., on the distribution of 



bats, 354. 

 Transitions in varieties rare, 155. 

 Trees on islands belong to peculiar 



orders, 352. 



with separated sexes, 90. 



Trifolium pratense, 68, 86. 



incarnatum, 86. 



Trigonia, 288. 

 Trilobites, 275. 



sudden extinction of, 288. 



Troglodytes, 218. 



analogous 



Tucutucu, blind, 124. 

 Tumbler pigeons, habits of, heredi- 

 tary, 192. 



young of, 400. 



Turkey-cock, brush of hair on 



breast, 82. 

 Turkey, naked skin on head, 177. 



young, wild, 194. 



Turnip and cabbage, 



variations of, 144. 

 Type, unity of, 185. 

 Types, succession of, in same 



areas, 304. 



Udders enlarged by use, 11. 



rudimentary, 405. 



Ulex, young leaves of, 395. 



Umbelliferse, outer and inner 

 florets of, 131. 



Unity of type, 185. 



Use, effects of, under domestica- 

 tion, 10. 



effects of, in a state of nature, 



122. 



Utility, how far important in the 

 construction of each part, 179. 



Valenciennes on fresh-water fish, 

 345. 



Variability -of mongrels and hy- 

 brids, 244. 



Variation under domestication, 7. 



caused by reproductive sy- 

 stem being affected by conditions 

 of life, 8. 



under nature, 41. 



laws of, 119. 



Variations appearat corresponding 

 ages, 13, 81. 



analogous in distinct species, 



144. 



Varieties, natural, 41. 

 struggle between, 69. 



domestic, extinction of, 102. 



transitional, rarity of, 155. 



when crossed, fertile, 240. 



when crossed, sterile, 242. 



classification of, 380. 



Verbascum, sterility of. 225. 



varieties of, crossed, 242. 



Verneuil, M. de, on the succession 



of species, 291. 

 Viola tricolor, 68. 

 Volcanic islands, denudation of, 



255. 

 Vulture, naked skin on head, 177. 



