INDEXAberrant groups, 429.Abyssinia, plants of, 375.Acclimatisation, 139.Affinities:of organic beings, 411.on groups of species suddenly appearing, 302, 305.Agassiz:on Amblyopsis, 139.on the glacial period, 366.on embryological succession, 338.on the embryos of vertebrata, 439.on embryological characters, 418.449.on parallelism of embryological development and geological succession,Algae of New Zealand, 376.productions allied to those of Europe, 371.Alligators, males, fighting, 88. Amblyopsis, blind fish, 139. America, North: boulders and glaciers of, 373.Analogy of variations, 159.South, no modern formations on west coast, 290. Ammonites, sudden extinction of, 321. Anagallis, sterility of, 247. Ancylus, 386. Animals:with thicker fur in cold climates, 133.not domesticated from being variable, 17. domestic, descended from several stocks, 19. acclimatisation of, 141. of Australia, 116. blind, in caves, 137. extinct, of Australia, 339.Aphides attended by ants, 211.Anomma, 240. Antarctic islands, ancient flora of, 399. Antirrhinum, 161. Ants: attending aphides, 211. slave-making instinct, 219. Ants, neuter, structure of, 236.Asclepias, pollen of, 193.Aphis, development of, 442. Apteryx, 182. Arab horses, 35, Aralo-Caspian Sea, 339. Archiac, M. de, on the succession of species, 325. Artichoke, Jerusalem, 142. Ascension, plants of, 389.animals of, 116.Asparagus, 359. Aspicarpa, 417. Asses, striped, 163. Ateuchus, 135, Audubon: on habits of frigate-bird, 185. on variation in birds'-nests, 212, on heron eating seeds, 387. Australia: dogs of, 215.Barberry, flowers of, 98.extinct animals of, 339. European plants in, 375. Azara on flies destroying cattle, 72. Azores, flora of, 363. Babington, Mr., on British plants, 48. Balancement of growth, 147. Bamboo with hooks, 197. Barrande, M.:how structure acquired, 180.on Silurian colonies, 313. on the succession of species, 325. on parallelism of palaeozoic formations, 328. on affinities of ancient species, 330. Barriers, importance of, 347. Batrachians on islands, 393. Bats: distribution of, 394.wingless, in Madeira, 135.Bear, catching water-insects, 184. Bee: sting of, 202. queen, killing rivals, 202. Bees fertilising flowers, 73. Bees: hive, not sucking the red clover, 95. cell-making instinct, 224. humble, cells of, 225. parasitic, 218. Beetles: with deficient tarsi, 135.of Madeira, Bermuda, and Galapagos, 390.Bentham, Mr.: on British plants, 48. on classification, 419. Berkeley, Mr., on seeds in salt-water, 358. Bermuda, birds of, 391. Birds: acquiring fear, 212. annually cross the Atlantic, 364. colour of, on continents, 132. fossil, in caves of Brazil, 339. song of males, 89.on crossed geese, 253.transporting seeds, 361. waders, 386. wingless, 134, 182. with traces of embryonic teeth, 451. Bizcacha, 349. affinities of, 429. Bladder for swimming in fish, 190. Blindness of cave animals, 137, Blyth, Mr.: on distinctness of Indian cattle, 18. on striped Hemionus, 163.Brewer, Dr., on American cuckoo, 217.Boar, shoulder-pad of, 88. Borrow, Mr., on the Spanish pointer, 35. Bory St. Vincent on Batrachians, 393. Bosquet, M., on fossil Chthamalus, 304. Boulders, erratic, on the Azores, 363. Branchiae, 190. Brent, Mr.: on house-tumblers, 214. on hawks killing pigeons, 362. Britain, mammals of, 395.Cape of Good Hope, plants of, 110, 375.Bronn on duration of specific forms, 293. Brown, Robert, on classification, 414. Buckman on variation in plants, 10. Buzareingues on sterility of varieties, 270. Cabbage, varieties of, crossed, 99. Calceolaria, 251. Canary-birds, sterility of hybrids, 252. Cape de Verde islands, 398. Carrier-pigeons killed by hawks, 362.Cassini on flowers of compositae, 145. Catasetum, 424. Cats: with blue eyes, deaf, 12. variation in habits of, 91. curling tail when going to spring, 201. Cattle: destroying fir-trees, 71. destroyed by flies in La Plata, 72. breeds of, locally extinct, 111. fertility of Indian and European breeds, 254. Cave, inhabitants of, blind, 137.Chthamalinae, 288.Centres of creation, 352. Cephalopodae, development of, 442. Cervulus, 253. Cetacea, teeth and hair, 144. Ceylon, plants of, 375. Chalk formation, 322. Characters: divergence of, 111. sexual, variable, 156. adaptive or analogical, 427. Charlock, 76, Checks: to increase, 67. mutual, 71. Chickens, instinctive tameness of, 216.effects of, in checking increase of beings, 68.Chthamalus, cretacean species of, 304. Circumstances favourable: to selection of domestic products, 40. to natural selection, 101. Cirripedes: capable of crossing, 101. carapace aborted, 148. their ovigerous frena, 192. fossil, 304. larvae of, 440. Classification, 413. Clift, Mr., on the succession of types, 339. Climate: adaptation of, to organisms, 139.Conditions, slight changes in, favourable to fertility, 267.Cobites, intestine of, 190. Cockroach, 76. Collections, palaeontological, poor, 287. Colour: influenced by climate, 132. in relation to attacks by flies, 198. Columba livia, parent of domestic pigeons, 23. Colymbetes, 386. Compensation of growth, 147. Compositae: outer and inner florets of, 144. male flowers of, 451. Conclusion, general, 480. Coot, 185. Coral:Crustacea of New Zealand, 376.islands, seeds drifted to, 360. reefs, indicating movements of earth, 309. Corn-crake, 185. Correlation: of growth in domestic productions, 11. of growth, 143, 198. Cowslip, 49. Creation, single centres of, 352. Crinum, 250. Crosses, reciprocal, 258. Crossing: of domestic animals, importance in altering breeds, 20. advantages of, 96. unfavourable to selection, 102. Crustacean, blind, 137.on umbelliferae, 146.Cryptocerus, 238. Ctenomys, blind, 137. Cuckoo, instinct of, 216. Currants, grafts of, 262. Currents of sea, rate of, 359. Cuvier: on conditions of existence, 206. on fossil monkeys, 303. Cuvier, Fred., on instinct, 208. Dana, Professor: on blind cave-animals, 139. on relations of crustaceans of Japan, 372. on crustaceans of New Zealand, 376. De Candolle: on struggle for existence, 62.of oldest rocks, 308.on general affinities, 430. De Candolle, Alph.: on low plants, widely dispersed, 406. on widely-ranging plants being variable, 53. on naturalisation, 115. on winged seeds, 146. on Alpine species suddenly becoming rare, 175. on distribution of plants with large seeds, 360. on vegetation of Australia, 379. on fresh-water plants, 386. on insular plants, 389. Degradation of coast-rocks, 282. Denudation: rate of, 285.domestic instincts of, 213.Development of ancient forms, 336. Devonian system, 334. Dianthus, fertility of crosses, 256. Dirt on feet of birds, 362. Dispersal: means of, 356. during glacial period, 365. Distribution: geographical, 346. means of, 356. Disuse, effects of, under nature, 134. Divergence of character, 111. Division, physiological, of labour, 115. Dogs: hairless, with imperfect teeth, 12. descended from several wild stocks, 18.Dung-beetles with deficient tarsi, 135.inherited civilisation of, 215. fertility of breeds together, 254. of crosses, 268, proportions of, when young, 444. Domestication, variation under, 7. Downing, Mr., on fruit-trees in America, 85. Downs, North and South, 285. Dragon-flies, intestines of, 190. Drift-timber, 360. Driver-ant, 240. Drones killed by other bees, 202. Duck: domestic, wings of, reduced, 11. logger-headed, 182. Duckweed, 385. Dugong, affinities of, 414.Elephant:Dyticus, 386. Earl, Mr. W., on the Malay Archipelago, 395. Ears: drooping, in domestic animals, 11. rudimentary, 454. Earth, seeds in roots of trees, 361. Eciton, 238. Economy of organisation, 147. Edentata: teeth and hair, 144. fossil species of, 339. Edwards, Milne: on physiological divisions of labour, 115. on gradations of structure, 194. on embryological characters, 418. Eggs, young birds escaping from, 87. Electric organs, 192.and Cautley on mammals of sub-Himalayan beds, 340.rate of increase, 64. of glacial period, 141. Embryology, 439. Existence: struggle for, 60. conditions of, 206. Extinction: as bearing on natural selection, 109. of domestic varieties, 111. 317. Eye: structure of, 187. correction for aberration, 202. Eyes reduced in moles, 137. Fabre, M., on parasitic sphex, 218. Falconer, Dr.: on naturalization of plants in India, 65. on fossil crocodile, 313. on elephants and mastodons, 334,ganoid, now confined to fresh water, 107.Falkland Island, wolf of, 393. Faults, 285. Faunas, marine, 348. Fear, instinctive, in birds, 212. Feet of birds, young molluscs adhering to, 385. Fertility: of hybrids, 249. from slight changes in conditions, 267. of crossed varieties, 267. Fir-trees: destroyed by cattle, 71. pollen of, 203. Fish: flying, 182. teleostean, sudden appearance of, 305. eating seeds, 362, 387. fresh-water, distribution of, 384. Fishes: electric organs of, 192.Forests, changes in, in America, 74.ganoid, living in fresh water, 321. of southern hemisphere, 376. Flight, powers of, how acquired, 182. Flowers: structure of, in relation to crossing, 97. of compositae and umbelliferae, 144. Forbes, E.: on colours of shells, 132. on abrupt range of shells in depth, 175. on poorness of palaeontological collections, 287. on continuous succession of genera, 316. on continental extensions, 357. on distribution during glacial period, 366, on parallelism in time and space, 409.Fuci, crossed, 258.Formation, Devonian, 334. Formations: thickness of, in Britain, 284. intermittent, 290. Formica rufescens, 219. Formica sanguinea, 219. Formica flava, neuter of, 239. Frena, ovigerous, of cirripedes, 192. Fresh-water productions, dispersal of, 383. Fries on species in large genera being closely allied to other species, 57. Frigate-bird, 185. Frogs on islands, 393. Fruit-trees: gradual improvement of, 37. in United States, 85. varieties of, acclimatised in United States, 142.on homologous organs, 434.Fur, thicker in cold climates, 133. Furze, 439. Galapagos Archipelago: birds of, 390. productions of, 398, 400. Galeopithecus, 181. Game, increase of, checked by vermin, 68. Gartner: on sterility of hybrids, 247, 255. on reciprocal crosses, 258. on crossed maize and verbascum, 270. on comparison of hybrids and mongrels, 272. Geese: fertility when crossed, 253. upland, 185. Genealogy important in classification, 425. Geoffrey St. Hilaire: on balancement, 147. Geoffrey St. Hilaire, Isidore:Gould, Mr.:on variability of repeated parts, 149. on correlation in monstrosities, 11. on correlation, 144. on variable parts being often monstrous, 155. Geographical distribution, 346. Geography, ancient, 487. Geology: future progress of, 487. imperfection of the record, 279. Giraffe, tail of, 195. Glacial period, 365. Gmelin on distribution, 365. Gnathodon, fossil, 368. Godwin-Austen, Mr., on the Malay Archipelago, 299. Goethe on compensation of growth, 147. Gooseberry, grafts of, 262. Gould, Dr. A., on land-shells, 397.correlation of, in domestic products, 11.on colours of birds, 132. on birds of the Galapagos, 398. on distribution of genera of birds, 404. Gourds, crossed, 270. Grafts, capacity of, 261. Grasses, varieties of, 113. Gray, Dr. Asa: on trees of United States, 100. on naturalised plants in the United States, 115. on rarity of intermediate varieties, 176. on Alpine plants, 365. Gray, Dr. J. E., on striped mule, 165. Grebe, 185. Groups, aberrant, 429. Grouse: colours of, 84. red, a doubtful species, 49. Growth: compensation of, 147. correlation of, 143. Habit:Heron, Sir R., on peacocks, 89.effect of, under domestication, 11. effect of, under nature, 134. diversified, of same species, 183. Hair and teeth, correlated, 144. Harcourt, Mr. E. V., on the birds of Madeira, 391. Hartung, M., on boulders in the Azores, 363. Hazel-nuts, 359. Hearne on habits of bears, 184. Heath, changes in vegetation, 72, Heer, O., on plants of Madeira, 107. Helix pomatia, 397. Helosciadium, 359. Hemionus, striped, 163. Herbert, W.: on struggle for existence, 62. on sterility of hybrids, 249. Hermaphrodites crossing, 96. Heron eating seed, 387.on relations of flora of South America, 379.Heusinger on white animals not poisoned by certain plants, 12. Hewitt, Mr., on sterility of first crosses. 264. Himalaya: glaciers of, 373. plants of, 375. Hippeastrum, 250. Holly-trees, sexes of, 93. Hollyhock, varieties of, crossed, 271. Hooker, Dr., on trees of New Zealand, 100. Hooker, Dr.: on acclimatisation of Himalayan trees, 140. on flowers of umbelliferae, 145. on glaciers of Himalaya, 373. on algae of New Zealand, 376. on vegetation at the base of the Himalaya, 378. on plants of Tierra del Fuego, 374, 378. on Australian plants, 375, 399. on flora of the Antarctic lands, 381, 399.Hutton, Captain, on crossed geese, 253.on the plants of the Galapagos, 391, 398. Hooks: on bamboos, 197. to seeds on islands, 392. Horner, Mr., on the antiquity of Egyptians, 18. Horns, rudimentary, 454. Horse, fossil, in La Plata, 318. Horses: destroyed by flies in La Plata, 72. striped, 163. proportions of, when young, 445. Horticulturists, selection applied by, 32. Huber on cells of bees, 230. Huber, P.: on reason blended with instinct, 208. on habitual nature of instincts, 208. on slave making ants, 219. on Melipona domestica, 225. Humble-bees, cells of, 225. Hunter, J., on secondary sexual characters, 150. Huxley, Professor:Intercrossing, advantages of, 96.on structure of hermaphrodites, 101. on embryological succession, 338. on homologous organs, 438. on the development of aphis, 442. Hybrids and mongrels compared, 272. Hybridism, 245. Hydra, structure of, 190. Ibla, 148. Icebergs transporting seeds, 363. Increase, rate of, 63. Individuals: numbers favourable to selection, 102. many, whether simultaneously created, 356. Inheritance: laws of, 12. at corresponding ages, 14, 86. Insects: colour of, fitted for habitations, 84. sea-side, colours of, 132. blind, in caves, 138. luminous, 193. neuter, 236. Instinct, 207. Instincts, domestic, 213. Islands, oceanic, 388.of Madeira, naturalised, 402.Isolation favourable to selection, 104. Japan, productions of, 372. Java, plants of, 375. Jones, Mr. J. M., on the birds of Bermuda, 391. Jussieu on classification, 417. Kentucky, caves of, 137. Kerguelen-land, flora of, 381, 399. Kidney-bean, acclimatisation of, 142. Kidneys of birds, 144. Kirby on tarsi deficient in beetles, 135. Knight, Andrew, on cause of variation, 7. Kolreuter: on the barberry, 98. on sterility of hybrids, 247. on reciprocal crosses, 258. on crossed varieties of nicotiana, 271. on crossing male and hermaphrodite flowers, 451. Lamarck on adaptive characters, 427. Land-shells: distribution of, 397. Languages, classification of, 422.Lund and Clausen on fossils of Brazil, 339.Lapse, great, of time, 282. Larvae, 440. Laurel, nectar secreted by the leaves, 92. Laws of variation, 131. Leech, varieties of, 76. Leguminosae, nectar secreted by glands, 92. Lepidosiren, 107, 330. Life, struggle for, 60. Lingula, Silurian, 306. Linnaeus, aphorism of, 413. Lion: mane of, 88. young of, striped, 439. Lobelia fulgens, 73, 98, Lobelia, sterility of crosses, 250. Loess of the Rhine, 384. Lowness of structure connected with variability, 149. Lowness, related to wide distribution, 406. Lubbock, Mr., on the nerves of coccus, 46. Lucas, Dr. P.: on inheritance, 12. on resemblance of child to parent, 275. Lyell, Sir C.: on the struggle for existence, 62.fossil land-shells of, 339.on modern changes of the earth, 95. on measure of denudation, 283. on a carboniferous land-shell, 289. on fossil whales, 303. on strata beneath Silurian system, 307. on the imperfection of the geological record, 310. on the appearance of species, 312. on Barrande's colonies, 313. on tertiary formations of Europe and North America, 323. on parallelism of tertiary formations, 328. on transport of seeds by icebergs, 363. on great alternations of climate, 382. on the distribution of fresh-water shells, 385. on land-shells of Madeira, 402. Lyell and Dawson on fossilized trees in Nova Scotia, 296. Macleay on analogical characters, 427. Madeira: plants of, 107. beetles of, wingless, 135. birds of, 390. Magpie tame in Norway, 212.Miller, Professor, on the cells of bees, 226.Maize, crossed, 270. Malay Archipelago: compared with Europe, 299. mammals of, 395. Malpighiaceae, 417. Mammae, rudimentary, 451. Mammals: fossil, in secondary formation, 303. insular, 393. Man, origin of races of, 199. Manatee, rudimentary nails of, 454. Marsupials: of Australia, 116. fossil species of, 339. Martens, M., experiment on seeds, 360. Martin, Mr. W. C., on striped mules, 165. Matteuchi on the electric organs of rays, 193. Matthiola, reciprocal crosses of, 258. Means of dispersal, 356. Melipona domestica, 225. Metamorphism of oldest rocks 308. Mice: destroying bees, 74. acclimatisation of, 141. Migration, bears on first appearance of fossils, 296. Mirabilis, crosses of, 258. Missel-thrush, 76.Nails, rudimentary, 453.Misseltoe, complex relations of, 3. Mississippi, rate of deposition at mouth, 284. Mocking-thrush of the Galapagos, 402. Modification of species, how far applicable, 483. Moles, blind, 137. Mongrels: fertility and sterility of, 267. and hybrids compared, 272. Monkeys, fossil, 303, Monocanthus, 424. Mons, Van, on the origin of fruit-trees, 29, 39. Moquin-Tandon on sea-side plants, 132. Morphology, 434. Mozart, musical powers of, 209. Mud, seeds in, 386. Mules, striped, 165. Muller, Dr. F., on Alpine Australian plants, 375. Murchison, Sir R.: on the formations of Russia, 289. on azoic formations, 307. on extinction, 317. Mustela vison, 179. Myanthus, 424. Myrmecocystus, 238. Myrmica, eyes of, 240. Natural history: future progress of, 484.of extreme perfection, 186,selection, 80. system, 413. Naturalisation: of forms distinct from the indigenous species, 115. in New Zealand, 201. Nautilus, Silurian, 306. Nectar of plants, 92. Nectaries, how formed, 92. Nelumbium luteum, 387. Nests, variation in, 212. Neuter insects, 236. Newman, Mr., on humble-bees, 74. New Zealand: productions of, not perfect, 201. naturalised products of, 337. fossil birds of, 339. glacial action in, 373, crustaceans of, 376. algae of, 376. number of plants of, 389. flora of, 399. Nicotiana: crossed varieties of, 271. certain species very sterile, 257. Noble, Mr., on fertility of Rhododendron, 251. Nodules, phosphatic, in azoic rocks, 307, Oak, varieties of, 50. Onites apelles, 135. Orchis, pollen of, 193, Organs: electric, of fishes, 192.Pallas on the fertility of the wild stocks of domestic animals, 253.of little importance, 194. homologous, 434. rudiments of, 450. Ornithorhynchus, 107, 416. Ostrich: not capable of flight, 134. habit of laying eggs together, 218. American, two species of, 349. Otter, habits of, how acquired, 179. Ouzel, water, 185. Owen, Professor: on birds not flying, 134. on vegetative repetition, 149. on variable length of arms in ourang-outang, 150. on the swim-bladder of fishes, 191. on electric organs, 192. on fossil horse of La Plata, 319. on relations of ruminants and pachyderms, 329. on fossil birds of New Zealand, 339. on succession of types, 339. on affinities of the dugong, 414. on homologous organs, 435. on the metamorphosis of cephalopods and spiders, 442. Pacific Ocean, faunas of, 348. Paley on no organ formed to give pain, 201.with feathered feet and skin between toes, 12.Paraguay, cattle destroyed by flies, 72. Parasites, 217. Partridge, dirt on feet, 362. Parts: greatly developed, variable, 150. degrees of utility of, 201. Parus major, 183. Passiflora, 251. Peaches in United States, 85. Pear, grafts of, 261. Pelargonium: flowers of, 145. sterility of, 251. Pelvis of women, 144, Peloria, 145. Period, glacial, 365. Petrels, habits of, 184. Phasianus, fertility of hybrids, 253. Pheasant, young, wild, 216. Philippi on tertiary species in Sicily, 312. Pictet, Professor: on groups of species suddenly appearing, 302, 305. on rate of organic change, 313. on continuous succession of genera, 316. on close alliance of fossils in consecutive formations, 335. on embryological succession, 338. Pierce, Mr., on varieties of wolves, 91. Pigeons:Poison, similar effect of, on animals and plants, 484.breeds described, and origin of, 20. breeds of, how produced, 39, 42. tumbler, not being able to get out of egg, 87. reverting to blue colour, 160. instinct of tumbling, 214. carriers, killed by hawks, 362. young of, 445. Pistil, rudimentary, 451. Plants: poisonous, not affecting certain coloured animals, 12. selection applied to, 32. gradual improvement of, 37. not improved in barbarous countries, 38. destroyed by insects, 67. in midst of range, have to struggle with other plants, 77. nectar of, 92, fleshy, on sea-shores, 132. fresh-water, distribution of, 386. low in scale, widely distributed, 406. Plumage, laws of change in sexes of birds, 89. Plums in the United States, 85. Pointer dog: origin of, 35. habits of, 213. Poison not affecting certain coloured animals, 12. Pollen of fir-trees, 203,Reproduction, rate of, 63.Poole, Col., on striped hemionus, 163. Potamogeton, 387. Prestwich, Mr., on English and French eocene formations, 328. Primrose, 49. sterility of, 247. Primula, varieties of, 49. Proteolepas, 148. Proteus, 139. Psychology, future progress of, 488. Quagga, striped, 165. Quince, grafts of, 261. Rabbit, disposition of young, 215. Races, domestic, characters of, 16. Race-horses: Arab, 35. English, 356. Ramond on plants of Pyrenees, 368. Ramsay, Professor: on thickness of the British formations, 284. on faults, 285. Ratio of increase, 63. Rats: supplanting each other, 76. acclimatisation of, 141. blind in cave, 137. Rattle-snake, 201. Reason and instinct, 208. Recapitulation, general, 459. Reciprocity of crosses, 258. Record, geological, imperfect, 279. Rengger on flies destroying cattle, 72.nutriment in, 77.Resemblance to parents in mongrels and hybrids, 273. Reversion: law of inheritance, 14. in pigeons to blue colour, 160. Rhododendron, sterility of, 251. Richard, Professor, on Aspicarpa, 417. Richardson, Sir J.: on structure of squirrels, 180. on fishes of the southern hemisphere, 376. Robinia, grafts of, 262. Rodents, blind, 137. Rudimentary organs, 450. Rudiments important for classification, 416. Sageret on grafts, 262. Salmons, males fighting, and hooked jaws of, 88. Salt-water, how far injurious to seeds, 358. Saurophagus sulphuratus, 183. Schiodte on blind insects, 138. Schlegel on snakes, 144 Sea-water, how far injurious to seeds, 358. Sebright, Sir J.: on crossed animals, 20. on selection of pigeons, 31. Sedgwick, Professor, on groups of species suddenly appearing, 302. Seedlings destroyed by insects, 67. Seeds: winged, 146.on neuter ants, 239.power of resisting salt-water, 358. in crops and intestines of birds, 361. eaten by fish, 362, 387. in mud, 386. hooked, on islands, 392. Selection: of domestic products, 29. principle not of recent origin, 33. unconscious, 34. natural, 80. sexual, 87. natural, circumstances favourable to, 101, Sexes, relations of, 87. Sexual: characters variable, 156. selection, 87. Sheep: Merino, their selection, 31. two sub-breeds unintentionally produced, 36. mountain, varieties of, 76. Shells: colours of, 132. littoral, seldom embedded, 288. fresh-water, dispersal of, 385. of Madeira, 391, land, distribution of, 397. Silene, fertility of crosses, 257. Silliman, Professor, on blind rat, 137. Skulls of young mammals, 197, 437. Slave-making instinct, 219. Smith, Col. Hamilton, on striped horses, 164. Smith, Mr. Fred.: on slave-making ants, 219.of certain varieties, 269.Smith, Mr., of Jordan Hill, on the degradation of coast-rocks, 283. Snap-dragon, 161. Somerville, Lord, on selection of sheep, 31. Sorbus, grafts of, 262. Spaniel, King Charles's breed, 35. Species: polymorphic, 46. common, variable, 53. in large genera variable, 54. groups of, suddenly appearing, 302, 306. beneath Silurian formations, 306. successively appearing, 312. changing simultaneously throughout the world, 322. Spencer, Lord, on increase in size of cattle, 35. Sphex, parasitic, 218. Spiders, development of, 442. Spitz-dog crossed with fox, 268. Sports in plants, 9. Sprengel, C. C.: on crossing, 98. on ray-florets, 145. Squirrels, gradations in structure, 180. Staffordshire, heath, changes in, 72. Stag-beetles, fighting, 88. Sterility: from changed conditions of life, 9. of hybrids, 246. laws of, 254. causes of, 263. from unfavourable conditions, 265. St. Helena, productions of, 389.Thuret, M., on crossed fuci, 258.St. Hilaire, Aug., on classification, 418. St. John, Mr., on habits of cats, 91. Sting of bee, 202. Stocks, aboriginal, of domestic animals, 18, Strata, thickness of, in Britain, 284. Stripes on horses, 163. Structure, degrees of utility of, 201. Struggle for existence, 60. Succession, geological, 312. Succession of types in same areas, 338. Swallow, one species supplanting another, 76. Swim-bladder, 190. System, natural, 413. Tail: of giraffe, 195. of aquatic animals, 196. rudimentary, 454. Tarsi deficient, 135. Tausch on umbelliferous flowers, 146. Teeth and hair: correlated, 144. embryonic, traces of, in birds, 451. rudimentary, in embryonic calf, 450, 480. Tegetmeier, Mr., on cells of bees, 228, 233. Temminck on distribution aiding classification, 419. Thouin on grafts, 262. Thrush: aquatic species of, 185. mocking, of the Galapagos, 402. young of, spotted, 439. nest of, 243. Thwaites, Mr., on acclimatisation, 140.effects of, under domestication, 11.Tierra del Fuego: dogs of, 215. plants of, 374, 378. Timber-drift, 360. Time, lapse of, 282. Titmouse, 183. Toads on islands, 393. Tobacco, crossed varieties of, 271. Tomes, Mr., on the distribution of bats, 394. Transitions in varieties rare, 172. Trees: on islands belong to peculiar orders, 392. with separated sexes, 99. Trifolium pratense, 73, 94. Trifolium incarnatum, 94. Trigonia, 321. Trilobites, 306. sudden extinction of, 321, Troglodytes, 243. Tucutucu, blind, 137. Tumbler pigeons: habits of, hereditary, 214. young of, 446, Turkey-cock, brush of hair on breast, 90. Turkey: naked skin on head, 197. young, wild, 216. Turnip and cabbage, analogous variations of, 159. Type, unity of, 206. Types, succession of, in same areas, 338. Udders: enlarged by use, 11. rudimentary, 451. Ulex, young leaves of, 439. Umbelliferae, outer and inner florets of, 144. Unity of type, 206. Use: effects of, in a state of nature, 134.Water-hen, 185.Utility, how far important in the construction of each part, 199. Valenciennes on fresh-water fish, 384. Variability of mongrels and hybrids, 274. Variation: under domestication, 7. caused by reproductive system being affected by conditions of life, 8. under nature, 44. laws of, 131. Variations: appear at corresponding ages, 14, 86. analogous in distinct species, 159. Varieties: natural, 44. struggle between, 75. domestic, extinction of, 111. transitional, rarity of, 172. when crossed, fertile, 267. when crossed, sterile, 269. classification of, 423. Verbascum: sterility of, 251. varieties of, crossed, 270. Verneuil, M. de, on the succession of species, 325. Viola tricolor, 73. Volcanic islands, denudation of, 284. Vulture, naked skin on head, 197. Wading-birds, 386. Wallace, Mr.: on origin of species, 2. on law of geographical distribution, 355. on the Malay Archipelago, 395. Wasp, sting of, 202. Water, fresh, productions of, 383. Waterhouse, Mr.: on Australian marsupials, 116.on insular insects, 389.on greatly developed parts being variable, 150. on the cells of bees, 225. on general affinities, 429. Water-ouzel, 185. Watson, Mr. H. C.: on range of varieties of British plants, 58. on acclimatisation, 140. on flora of Azores, 363. on Alpine plants, 367, 376. on rarity of intermediate varieties, 176. Weald, denudation of, 285. Web of feet in water-birds, 185. West Indian islands, mammals of, 395. Westwood: on species in large genera being closely allied to others, 57. on the tarsi of Engidae, 157. on the antennae of hymenopterous insects, 416. Whales, fossil, 303. Wheat, varieties of, 113. White Mountains, flora of, 365. Wings, reduction of size, 134. Wings: of insects homologous with branchiae, 191. rudimentary, in insects, 451. Wolf: crossed with dog, 214. of Falkland Isles, 393. Wollaston, Mr.: on varieties of insects, 48. on fossil varieties of land-shells in Madeira, 52. on colours of insects on sea-shore, 132. on wingless beetles, 135. on rarity of intermediate varieties, 176. on land-shells of Madeira, naturalised, 402.Zebra, stripes on, 163.Wolves, varieties of, 90. Woodpecker: habits of, 184. green colour of, 197. Woodward, Mr.: on the duration of specific forms, 293. on the continuous succession of genera, 316. on the succession of types, 339. World, species changing simultaneously throughout, 322. Wrens, nest of, 243. Youatt, Mr.: on selection, 31. on sub-breeds of sheep, 36. on rudimentary horns in young cattle, 454.
THE END.