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 
the 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 
I 
Icterus 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 
Rev. J. G. Gulick on, 147 
when ineffective, 150 
Ituna Ilione and Thyridia megisto, 
figures of wings of, 251 
J 
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 
K 
Kerguelen Island, wingless insects 
of, 106 
Kerivoula picta, protective colour of, 
201 
