BLIND CAVE-ANIMALS 329 
which (Caméarus) 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 (Azo- 
phthalmus) belonging to the family of Caradcdae, or ground- 
beetles, from the American caves; while those of France 
and Ireland have yielded a blind and colourless spring-tail 
(Lipura). 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 Szme//a (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 
