BLIND CAVE-ANIMALS 327 
colourless; but its sense of hearing is extraordinarily 
developed. In the typical form this fish has a small pair 
of pelvic fins, but in some examples (which have been 
referred to a distinct genus under the name of Typhlichthys) 
these are wanting. The maximum length is five inches. 
Prof. Cope writes that if these fish “be not alarmed, 
they come to the surface to feed, and swim in full sight 
like white aquatic ghosts. They are then easily taken by 
hand or net, if perfect silence is observed, for they are 
unconscious of the presence of an enemy except through 
the medium of hearing. This sense is, however, evidently 
very acute, for at any noise they turn suddenly downward, 
and hide beneath stones, etc., at the bottom. They must 
take much of their food near the surface, as the life of the 
depths is apparently very sparse.” 
The only other genus in the family is known as Cholo- 
gaster, and differs from the last in the retention of small 
external eyes, and likewise in the skin being coloured. 
Pelvic fins are absent, and the front of the head is provided 
_ With two horn-like appendages. These small fish were first 
known from three examples taken in the ditches of the South 
Carolina rice-fields ; but another specimen was caught in a 
well in Lebanon County, Tennessee, in the year 1854. They 
appear to have taken to a partially subterranean life com- 
paratively recently, and therefore retain their eyes and dark 
coloration. 
Although these cave-fish are clearly allies of the cyprino- 
donts, there is no evidence to show that they are directly 
descended from any member of that family. A clear descent 
is, however, indicated by a very remarkable family of fishes 
known as the Ophiditdae, which are near relatives of the 
cod tribe. With the single exception of the cave-fish of 
the caves of Cuba (Lucifuga dentata), all the members of 
