486 



INDEX 



Horse tribe, pedigree of, 384 

 ancestral forms of, 386 

 Humming-birds, recognition marks of, 



226 

 Huth, Mr., on close interbreeding, 



160 

 Huxley, Professor on the struggle 

 for existence, 37 

 on fossil crocodiles, 383 

 on anatomical peculiarities of 



tlie horse tribe, 384 

 on development of vertebrates, 



448 

 on early man, 456 

 on brains of man and the gorilla, 

 457 

 Hybridity, remarks on facts of, 166 



summary on, 184 

 Hybrids, infertility of, supposed test 

 of distinct species, 152 

 fertility of, 159 

 fertile among animals, 162 

 between sheep and goat, 162 

 fertile between distinct species 



of moths, 163 

 fertile among plants, 163 

 Hymenopus bicornis, resembling 

 flower, 212 



Icteeus Baltimore, diagram showing 

 proportionate numbers which 

 vary, 63 

 Imitative resemblances, how pro- 

 duced, 205 

 Increase of organisms in a geometrical 



ratio, 25 

 Inedible fruits rarely coloured, 308 

 Insect and self-fertilisation, alterna- 

 tion of, in flowers, 328 

 Insect-fertilisation, facts relating to, 



316 

 Insects, coloured for recognition, 226 

 warning colours of, 233 

 sexual coloration of, 269 

 importance of dull colours to 



female, 272 

 visiting one kind of flower at 



a time, 318 

 and flowers, the most brilliant 

 not found together, 335 



Insects, no proof of love of colour by, 

 336 

 and birds at sea, 357 

 in mid-ocean, 359 

 at great altitudes, 360 

 geological distribution of, 403 

 ancestral in Silurian, 405 

 fossil support evolution, 405 

 Instability of useless characters, 138 

 Instinct, the theory of, 441 

 Insular organisms illustrate powers 



of dispersal, 354 

 Interbreeding, close, injurious effects 

 of, 160 

 supposed evil results of close, 

 326 

 Intercrossing, swamping effects of, 

 142 

 not necessarily useful, 325 

 Intermediate forms, why not found, 



380 

 Islands, all oceanic are volcanic or 



coralline, 342 

 Isle of Man, small butterflies of, 106 

 Isolation, the importance of, 119 

 to prevent intercrossing, 144 

 by variations of habits, etc., 145 

 Eev. J. G. Gulick on, 147 

 when ineffective, 150 

 Ituna Ilione and Thyridia megisto, 

 figures of wings of, 251 



Jacobin, 93 



Jenyns, Rev. L., on internal varia- 

 tions of mammalia, 69 



Jordan, Mons. A., on varieties of 

 Draba verna, 77 



Judd, Professor, on dust fallen at 

 Genoa, 363 

 on Hungarian fossil lacustrine 

 shells, 381 



Kerguelen Island, wingless insects 



of, 106 

 Kerivoula picta, protective colour of, 



201 



