nts, 163

Hymenopus bicornis, resembling flower, 212

=I=

Icterus Baltimore, diagram showing proportionate numbers which
vary, 63

Imitative resemblances, how produced, 205

Increase of organisms in a geometrical ratio, 25

Inedible fruits rarely coloured, 308

Insect and self-fertilisation, alternation 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 variations 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

Kerner, Professor, on use of external characters of plants, 133
on seeds found on glaciers, 366

Kingfishers illustrating divergence of character, 109

=L=

Lacerta muralis, diagram of variation of, 47

Lagopus scoticus, origin of, 107

Lamarck, on origin of species, 3

Land debris deposited near coasts, 343
and ocean, diagram showing comparative height and depth of, 345

Large animals, cause of extinction of, 394

Larvae of moths, variability of, 46

Laughers, Frill-backs, Nuns, Spots, and Swallows, 93

Law of relation of colour and nest, 278, 279

Laws of animal coloration, 296

Lawson Tait, on uses of tails,