Colour, its inconstancy in insects found near the sea, 57, 58. ---- of insects, affected by isolation, 88. _Colymbetes_, a species of, captured forty-five miles from shore, 149, 150. Compensation, generally apparent when an insect is deprived of an organ or sense, 81. _Coranus subapterus_, Curt., the development of the wings of, 101. Cordillera, Mr. Darwin on the fauna of the, 145. _Corylophus_, apterous in Madeira, 82. _Criomorphus_, Curtis, referable to the genus _Delphax_, 45. _Cyclostoma lucidum_, Lowe, its extinction in Porto Santo, 131. _Cynthia Cardui_, Linn., unaffected by climate, 32. _Cynucus_, a species of, seventeen miles from shore, 150. _Cyrtonota_, its concentration in S. America, 143. Darwin, Mr., on the fauna of the Galapagos, 23; relative proportions of the insect tribes in the tropics, 28, 29; on the insects of Tierra del Fuego, 47; on the natural features of Tierra del Fuego, 50; on the insects of Keeling Island, 55; on the insects of St. Helena, 55; on the insects of Ascension, 55; on the apterous condition of insular species, 86; on the fauna of the Cordillera, 145; on a _Calosoma_ captured at sea, 147; on insects captured in the sea, 149, 150; on the disappearance of animals before more powerful ones than themselves, 178. Dawson, Rev. J. F., on a variety of _Bembidium saxatile_, 60. Definition of the term 'species,' 4; of the term 'variety,' 4. _Delphax_, on the development of the wings of, 45. _Dermestes vulpinus_, Fabr., unaffected by climate, 31. _Deucalion_, its occurrence on the Salvages and Dezertas, 125. _---- Desertarum_, Woll., its sedentary nature, 125, 126, 127. _Dichelus_, its concentration in S. Africa, 143. Differences, when to be regarded as specific, 6; too exclusively studied, 12. Diffusion, various means of, which operate on the insect tribes, 148. Disturbing agents, Prof. Henfrey on, 8. _Ditylus_, the same type of, indicated in the Canaries and Salvages, 124. Domesticated animals, pliable nature of, 187, 192. _Dromius arenicola_, Woll., representative of _D. obscuroguttatus_, 66. _---- fasciatus_, Gyll., its paleness near the sea, 63. _---- negrita_, Woll., perhaps an ultimate state of _D. glabratus_, 85. _---- obscuroguttatus_, Dufts., its changes in Madeira, 36, 37, 38; apterous in Madeira, 84. _---- sigma_, Rossi, its colour affected by isolation, 88, 89. Elevation, sometimes corresponds with latitude, 35, 114. _Ellipsodes glabratus_, Fabr., singular variety of, on one of the Madeira Islands, 88, 109. Elytra, connateness of, a variable character, 96. 'Endemic,' to what species the term is applicable, 118. Entomology, the study of, does not necessarily cramp the mind, 111. _Ephistemus_, apterous in Madeira, 82. _Eucalypti_, their concentration in Australia, 142.