" On my view we must suppose that
American animals, having in most cases ordinary powers of vision, slowly
migrated by successive generations from the outer world into the deeper and
deeper recesses of the Kentucky caves, as did European animals into the
caves of Europe. We have some evidence of this gradation of habit; for, as
Schiodte remarks: "We accordingly look upon the subterranean faunas as
small ramifications which have penetrated into the earth from the
geographically limited faunas of the adjacent tracts, and which, as they
extended themselves into darkness, have been accommodated to surrounding
circumstances. Animals not far remote from ordinary forms, prepare the
transition from light to darkness. Next follow those that are constructed
for twilight; and, last of all, those destined for total darkness, and
whose formation is quite peculiar." These remarks of Schiodte's it should
be understood, apply not to the same, but to distinct species. By the time
that an animal had reached, after numberless generations, the deepest
recesses, disuse will on this view have more or less perfectly obliterated
its eyes, and natural selection will often have effected other changes,
such as an increase in the length of the antennae or palpi, as a
compensation for blindness. Notwithstanding such modifications, we might
expect still to see in the cave-animals of America, affinities to the other
inhabitants of that continent, and in those of Europe to the inhabitants of
the European continent.
Pages:
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232