irts, 81.
Seeds, dissemination of, 65.
Seeley, Mr., on pterodactyles, 71.
Segmentation of skull, 172.
Segmentation of spine, 171.
Segments, similar, 160.
Self-existence, 252.
Semnopithecus, 139.
Sense, organ of, 51, 69, 74, 76.
Sensitiveness of generative system, 235.
Sepia, 77.
Serpents, poisonous, 50.
Sexual characters of apes, 49.
Sexual selection, 48.
Sharks, 83.
Shell-fish, beauty of, 54.
Shells of oysters, 88, 98.
Shielded grasshopper, 89.
Silurian strata, 140, 142.
Simultaneous modifications, 57.
Sirenia, 42
Sir John Lubbock, 198, 204.
Sir William Thomson, 136.
Sitaris, 46.
Six-shafted bird of Paradise, 90.
Skull bones, 153.
Skull segments, 172.
Sloth, windpipe of, 82.
Smithfield, wife-selling in, 198.
Snow, crystals of, 186.
Sole, 37.
Solenodon, 148.
Species, meaning of word, 2.
Spelerpes, 165.
Spencer, see Herbert Spencer.
Spider orchid, 55.
Spiders, flight of, 65.
Spine of Glyptodon, 110.
Spine, segmentation of, 172.
Squalidae, 38.
Squilla, 160.
Sterility of hybrids, 125.
Stings, 66.
Straining action of baleen, 41.
Struthious birds, 70, 151.
Sturgeon, 171.
Suarez, 18, 263.
Substantial forms, 186, 272.
Sufferings of beasts, 260.
Supernatural action, 252.
Supernatural action not to be looked for in nature, 15.
Supernumerary digits, 122, 181.
Syllis, 169, 211.
Symbolic conceptions, 251.
Symmetrical diseases, 182.
Syphilitic deposits, 183.

T.
Tadpole's beak, 83.
Tails of butterflies, 85.
Tapir, 123, 134.
Tarsal bones, 159, 198.
Teeth of Cetacea, 83.
Teeth of Insectivora, 68.
Teeth of kangaroo and Macroscelides, 69.
Teeth of seals, 83.
Teeth of sharks, 83.
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Teleology and evolution compatible, 273.
Tendrils of climbing plants, 107.
Tenia echinococcus, 170.
Teratology, 173.
Tetragonopterina, 146.
Thomson, Sir William, 136.
Thoracic fishes, 39.
Thorax of crustaceans, 79.
Thylacine, 67.
Tierra del Fuego, 192.
Tiger, sabre-toothed, 110.
Time required for evolution, 128.
Tope, 172.
Trabeculae cranii, 172.
Transitional forms, 128.
Transmutationism, 242.
Trevelyan, Sir J. Peacock, 100.
Trilobites, 135, 141, 171.
Tunicaries, 81.
Turbot, 37.
Turkey, effects of climate on, 100.
Turkish dog, 45.
Two-gilled cephalopods, 76.
Type, conformity to, 241.

U.
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