Chap. V. EFFECTS OF USE AND DISUSE. I43 



li^lit ; and, last of all, tlioso destined for total darkness, and 

 Aviiose formation is (juitc peculiar." These remarks of Schiiidte's, 

 it should be understood, apply not to the same, but to distinct 

 species. ]Jy the time that an animal had reached, after num- 

 berless generations, the deepest recesses, disuse will on this 

 view have more or less perfectly obliterated its eyes, and 

 natural selection will often have ell'ected other changes, such 

 as an increase in the length of the antenmu or palpi, as a com- 

 pensation for l)lindness. Notwithstanding such modifications, 

 we might expect still to sec in the cave-animals of America, 

 allinities to tlie other inhabitants of that continent, and in those 

 of Europe to the inhabitants of the European Continent. And 

 this is the case with some of the American cave-animals, as I 

 hi^ar from Prof. Dana ; and some of the European cave-insects 

 arc very closely allied to those of the surroimding countrv. It 

 woulil be most dillicult to give any rational explanation of the 

 allinities of the blind cave-animals to the other inhabitants of 

 the two continents on the ordinary view of their independent 

 creation. That several of the inhabitants of the caves of the 

 Old and New Worlds should l)e closely related, we might ex- 

 pect from the Avell-knowu relationship of most of their other 

 jiroductions. As a blind species of Bathyscia is found in abun- 

 dance on shady rocks far from caves, the loss of vision in the 

 cave-species of this one genus has probably had no relation to 

 its dark habitation ; and it is very natural that an insect al- 

 ready deprived of vision should readily become adapted to 

 dark caverns. Another blind genus (Anophthalmus) offers 

 this remarkable peculiarity: the several distinct species, as Mr. 

 MuiTay has remarked, iidiabit several distinct European caves 

 and likewise those of Kentucky, and the genus is found no- 

 v.here except in caves ; but it is possible that the progenitor 

 or progenitors of these several spec-ies, while furnished with 

 eyes, formerly may have ranged widely over both continents, 

 and then have become extinct, excepting in their ])resent se- 

 cluded abodes. Far from feeling surprise that some of the 

 rave-animals should be very anomalous, as Agassis has remarked 

 in regard to flu' blind fisli, the Amblyopsis, and as is the case 

 with the blind I'rotcus with refertMice to the reptiles of Europe, 

 1 am only surprised that more wrecks of ancient HA; have not 

 ]>ccn preserved, owing to tin; less severe competition to which 

 the inhabitants of these daik abodes must have been exposed. 



