INDEX. 



499 



Smith, Col. Hamilton, on striped 



horses, 144. 

 Smith, Mr. Fred., on slave-making 

 ants, 240. 

 on neuter ants, 256. 

 Smith, Dr., on the Polyzoa, 214. 

 Snake with tooth for cutting 



through egg-shell, 237. 

 Somerville, Lord, on selection of 



sheep, 25. 

 Sorbus, grafts of, 272. 

 So rex, 413. 



Spaniel, King Charles breed, 28. 

 Specialization of organs, 110. 

 Species, polymorphic, 39. 

 dominant, 48. 

 common, variable, 47. 

 in large genera variable, 49. 

 groups of, suddenly appearing, 



313, 316. 

 beneath Silurian formations, 317. 

 successively appearing, 320. 

 changing simultaneously through- 

 out the world, 330. 

 Spencer, Lord, on increase in size 



of cattle, 29. 

 Spencer, Herbert, Mr., on the first 

 steps in differentiation, 112. 

 on the tendency to an equilibrium 

 in all forces, 279. 

 Sphex, parasitic, 239. 

 Spiders, development of, 431. 

 Sports in plants, 9. 

 Sprengel, C. C, on crossing, 84. 



on ray-florets, 130. 

 Squalodon, 335. 

 Squirrels, gradations in structure, 



155. 

 Staffordshire, heath, changes in, 



62. 

 Stag-beetles, fighting, 77. 

 Starfishes, eyes of, 161. 



their pedicellarire, 213. 

 Sterility from changed conditions 

 of life, 8. 

 of hybrids, 262. 

 of hybrids, laws of, 267. 

 of hybrids, causes of, 273. 

 from unfavorable conditions, 277. 

 not induced through natural se- 

 lection, 274. 

 St. Helena, productions of, 385. 

 St. Hilaire, Aug., on variability of 

 certain plants, 194. 

 on classification, 407. 



St. Hilaire, Geoffroy, on balance- 



ment, 131. 

 on homologous organs, 423. 

 St. Hilaire, Isidore, on variability 



of repeated parts, 132. 

 on correlation, in monstrosities, 



10. 

 on correlation, 129. 

 on variable parts being often 



monstrous, 137. 

 St. John, Mr., on habits of cats, 



231. 

 Sting of bee, 182. 



Stocks, aboriginal, of domestic ani- 

 mals, 16. 

 Strata, thickness of, in Britain, 298. 

 Stripes on horses, 143. 

 Structure, degrees of utility of, 178. 

 Struggle for existence, 54. 

 Succession, geological, 322. 



of types in same areas, 344. 

 Swallow, one species supplanting 



another, 67. 

 Swaysland, Mr., on earth adhering 



to the feet of migratory birds, 



363. 

 Swifts, nests of, 252. 

 Swim-bladder, 165. 

 Switzerland, lake inhabitations of, 



15. 

 System, natural, 404. 



Tail of giraffe, 175. 

 of aquatic animals, 176. 

 prehensile, 209. 

 rudimentary, 441. 

 Tanais, dimorphic, 40. 

 Tarsi, deficient, 122. 

 Tausch, Dr., on umbelliferse, 193. 

 Teeth and hair correlated, 129. 

 rudimentary, in embryonic calf, 

 439, 464. 

 Tegetmeier, Mr., on cells of bees, 



246, 250. 

 Temminck, on distribution aiding 



classification, 408. 

 Tendrils, their development, 217. 

 Thompson, Sir W., on the age of 

 the habitable world, 317. 

 on the consolidation of the crust 

 of the earth, 453. 

 Thouin, on grafts, 272. 

 Thrush, aquatic species of, 159. 

 mocking, of the Galapagos, 395. 

 young of, spotted, 429. 



