BLIND CAVE- ANIMALS 329 



which (Cambarus) the eyes are rudimentary in the adult, 

 but larger in the young, thus affording conclusive evidence 

 of their descent from forms fully endowed with vision. 

 Prof. Cope has, however, described one cray-fish from the 

 Wyandotte Cave in which the eyes are completely wanting. 

 Among the insects, there is a totally blind beetle {Ano- 

 phthalmus) belonging to the family of Carabidae, or ground- 

 beetles, from the American caves; while those of France 

 and Ireland have yielded a blind and colourless spring-tail 

 (Lipurd). Wingless grasshoppers are abundant, but these, 

 at least generally, can see. Centipedes and spiders are 

 also common, one of the former from the Mammoth Cave 

 being totally blind, while others retain their eyes. In the 

 European species of cave-spiders (Parrhoma) the eyes are 

 excessively minute, and tend to become obsolete ; but it 

 is noteworthy that these creatures belong to a genus in 

 which the eyes are small even in the open-air kinds. 



It is thus apparent that all cave-animals are descended 

 from allied forms living in the outer world, and that in 

 many cases they belong to families which appear specially 

 adapted for modification to a subterranean existence. 



One of the most interesting discoveries is the close 

 alliance between creatures inhabiting caves widely remote 

 from one another. Writing of the animals of the Mitchels- 

 town Cave, Mr. G. H. Carpenter observes that the spring- 

 tail " is hardly to be separated from a species found in the 

 caves of Carniola, and the Sinella (another blind and bleached 

 insect) is almost identical with one inhabiting the caves of 

 North America ; while the spider is apparently the same as 

 a cave-dweller from the Mediterranean district of Southern 

 France, which probably occurs in the North American 

 caverns also. . . . Any possible geographical connection 

 which would permit the migration of subterranean animals 



