INDEX. 



535 



Shrew mouse, 440. 



Silene, infertility of crosses, 286. 



Silliman, Prof., on blind rat, 



131. 

 Sirenia, their affinities, 357. 

 Sitaris, metamorpliosis of, 465. 

 Skulls of young mammals, 188, 



453. 

 Slave-making instinct, 255. 

 Smith, Col. Hamilton, on striped 



horses, 153. 

 , Mr. Fred., on slave-making 



ants, 256. 



, on neuter ants, 273. 



Smith, Dr., on the Polyzoa, 228. 

 Snake with tooth for cutting 



through egg-shell, 253. 

 Somerville, Lord, on selection of 



sheep, 27. 

 Sorbus, grafts of, 290. 

 Sorex, 440. 



Spaniel, King Charles' breed, 30. 

 Specialization of organs, 117. 

 Species, polymorphic, 41. 



, dominant, 51. ; 



, common, variable, 50. 



in large genera variable, 52. 



, groups of, suddenly appear- 

 ing, 333, 337. 

 beneath Silurian formations, 



339. 

 - — successively appearing, 343. 

 changing simultaneously 



throughout the world, 352. 

 Spencer, Lord, on increase in size 



of cattle, 30. 

 , Herbert, Mr., on the first, 



steps in diffentiation, 120. 

 , on the tendency to an 



equilibrium in all forces, 297. 

 Sphex, parasitic, 255. 

 Spiders, development of, 460. 

 Sports in plants, 9. 

 Sprengel, C. C, on crossing, 89. 



, on ray-florets, 138. 



Squalodon, 357. 



Squirrels, gradations in structure, 



165. 

 Staffordshire, heath, changes in, 



66. 

 Stag-beetles, fighting, 81. 



Star fishes, eyes of, 171. 



, their pedicellarise, 227. 



Sterility from changed conditions 

 of life, 8. 



of hybrids, 279. 



, laws of. 284. 



, causes of, 391. 



, from unfavorable condi- 

 tions, 295. 



not induced through natural 



selection, 292. 



St. Helena, productions of, 410. 



St. Hilaire, Aug., on variability 

 of certain plants, 206. 



, on classification, 483. 



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

 247. 



Sting of bee, 194. 



Stocks, aboriginal, of domestic 

 animals, 17. 



Strata, thickness of, in Britain, 

 317. 



Stripes on horses, 152. 



Structure, degrees of utility of, 

 189. 



Struggle for existence, 57. 



Succession, geological, 343. 



of types in same areas, 367. 



Swallow, one species supplanting 

 another, 70. 



Swaysland, Mr., on earth adher- 

 ing to the feet of migratory 

 birds, 387. 



Swifts, nests of, 269. 



Swim-bladder, 175. 



Switzerland, lake inhabitations 

 of, 16. 



System, natural, 430. 



Tail of giraffe, 186. 



of aquatic animals, 187. 



, prehensible, 223. 



, rudimentary, 571. 



Tanais, dimorphic, 42. 



Tarsi, deficient, 129. 



Tausch, Dr., on umbelliferae, 205. 



Teeth and hair correlated, 137. 



, rudimentary, in embryonic 



calf, 467, 495. 

 Tegetmeier, Mr., on cells of bees, 



262, 267. 



