492 
INDEX 
Species, which vary little, 80 
closely allied inhabit distinct 
areas, 111 
vigour.and fertility of, how kept 
up,327 
Spencer, Mr. Herbert, on factors of 
organic evolution, 411 
on effects of disuse, 413 
on difficulty as toco-adaptation 
of parts, 417 
on direct action of environment, 
418 
Sphingidse, protective attitudes of 
larva;, 210 
Sphinx ligustri, general resemblance 
of larva to food plant, 202 
Spider, alluring coloration of, 211 
Spines, on origin of, 431 
rarity of, in oceaidc islands, 432 
Spiny plants abundant in South Africa 
and Chile, 433 
Spots a primitive ornamentation of 
animals, 2S9 
Sprengel on flowers and insects, 309 
Staphylinidse, protective habit of, 
210 
Sterility of mongrels, 165 
correlated with colour, etc., 168 
and natural selection, 173 
of hybrids produced by natural 
selection, 179 
Struggle for existence, 14 
among plants, 15 
for life, illustrations of, 18 
for existence on the pampas, 22 
for life between closely allied 
forms most severe, 33 
for existence, ethics of, 36 
how it acts among flowers, 328 
Summary of facts of colouring for 
protection and recognition, 
227 
Survival of the fittest, 11, 122, 123 
Swainson, definition of species, 2 
Swamping effects of intercrossing, 
142 
Sweden, destruction of grass by larvae 
of moths in, 17 
Swinhoe, Mr., on protective colouring 
of a bat, 201 
Symmetry, bilateral in colours of 
animals needful for recogni¬ 
tion, 217 
T 
Tails used as respirators, 136 
Tapirs, distribution of, 352 
Tegetmeier, Mr., on feeding habits of 
pigeons and fowls, 75 
on sparrows and crocuses, 75 
on curious correlations in 
pigeons, 140 
Tegumentary appendages and colour, 
291 
Thousand-fathom line divides oceanic 
from continental islands, 347 
the teachings of, 348 
map showing, 349 
Thwaites, Mr., on spread of Lantana 
mixta in Ceylon, 30 
Tiger, use of stripes of, 199 
Titmice as illustrating divergence, 
107 
Transformation of species of Crustacea, 
427 
Transmutationists, the early, 3 
Travers, Mr. W. L., on effects of in¬ 
troduced plants in New Zea¬ 
land, 29 
Trees, great variety of, in many 
forests, 36 
Trimen, Mr., on butterfly deceived by 
its mimic, 245 
on mimicry, 247 
Tropical animals, why brilliantly 
coloured, 299 
Tropics, no proof of lower tempera¬ 
ture of, 369 
Tropidorhynchi mimicked by orioles, 
263 
Trumpeter, 93 
Tumblers, 91 
Turbits and owls, 91 
Tylor, Mr. A., on Coloration in Ani 
mals and Plants, 285 
U 
Ungulates, origin of feet of, 423 
Use and disuse, effects of, overpowered 
by natural selection, 435 
Useless characters, 131 
not specific, 132 
