INDEX. 



501 



STRUCTURE. 





VIOLA. 



Structure, degrees of utility of, 2 



31. 



Tumbler pigeons, habits of, hereditary, 



Struggle for existence, 60. 





214. 



Succession, geological, 312. 





, young of, 446. 



Succession of types in same areas, 



338. 



Turkey-cock, brush of hair on breast, 



Swallow, one species supplantin 



g an- 



90. 



other, 76. 





Turkey, naked skin on head, 197. 



Swim-bladder, 190. 





, young, wild, 216. 



System, natural, 4-13. 





Turnip and cabbage, analogous variations 

 of, 159. 



T. 





Type, unity of, 206. 



Types, succession of, in same areas, 338. 



Tail of giraffe, 195. 







■ of aquatic animals, 196. 





IT. 



, rudimentary, 454. 







Tarsi deficient, 135. 





Udders enlarged by use, 11. 



Tausch on umbelliferous flowers, 



146. 



, rudimentary, 451. 



Teeth and hair correlated, 144. 





Ulex, young leaves of, 439. 



, embryonic, traces of, in 



birds, 



Umbellifera?, outer and inner florets of, 



451. 





144. 



, rudimentary, in embryonic calf, 



Unity of type, 206. 



450, 480. 





Use, effects of, under domestication, 11. 



Tegetmeier, Mr., on cells of bees 



, 228, 



, effects of, in a state of nature, 



233. 





134. 



Temminck on distribution aiding 



classi- 



Utility, how far important in the con- 



fication, 419. 





struction of each part, 199. 



Thouin on grafts, 262. 







Thrush, aquatic species of, 185. 





V. 



, mocking, of the Galapagos, 



402. 





, young of, spotted, 439. 





Valenciennes on fresh-water fish, 384. 



, nest of, 243. 





Variability of mongrels and hybrids, 



Thuret, M., on crossed fuci, 258. 





274. 



Thwaites, Mr., on acclimatisation 



140. 



Variation under domestication, 7. 



Tierra del Fuego, dogs of, 215. 





caused by reproductive system 



, plants of, 374, 378. 





being affected by conditions of life, 8. 



Timber-drift, 360. 





under nature, 44. 



Time, lapse of, 282. 





, laws of, 131. 



Titmouse, 183. 





Variations appear at corresponding ages, 



Toads on islands, 393. 





14, 86. 



Tobacco, crossed varieties of, 271 





■ , analogous in distinct species, 



Tomes, Mr., on the distribution of bats, 



159. 



394. 





Varieties, natural, 44. 



Transitions in varieties rare, 172. 





, struggle between, 75. 



Trees on islands belong to peculiar 



, domestic, extinction of, 111. 



orders, 392. 





, transitional, rarity of, 172. 



with separated sexes, 99. 





, when crossed, fertile, 267. 



Trifolium pratense, 73, 94. 





, when crossed, sterile, 269. 



incarnatum, 94. 





— — ■ , classification of, 423. 



Trigonia, 321 . 





Verbascum, sterility of, 251. 



Trilobites, 306. 





, varieties of, crossed, 270. 



, sadden extinction of, 321. 





Verneuil, M. de, on the succession of 



Troglodytes, 243. 





species, 325. 



Tucutucu, blind, 137. 





Viola tricolor, 73. 



