Tue OriIGIN oF CAavE Faunas. By C. H. EIGENMANN. 
[Abstract. ] 
There are two prominent views of the origin of the cave faunas and of 
their degenerate eyes. ; 
The following from Ray Lankester presents one of these views: Sup- 
posing a number of some species of arthropod or fish to be swept into a 
cavern or to be carried from less to greater depths in the sea, those indi- 
viduals with perfect eyes would follow the glimmer of light and eventu- 
ally escape to the outer air or the shallower depths, leaving behind those 
with imperfect eyes to breed in the dark place. A natural selection would 
thus be effected. In every succeeding generation this would be the case, 
“and even those with w sak but still seeing eyes would in the course of 
time escape, until only a pure race of eyeless or blind animals would be 
left in the cavern or deep sea. 
2. “The existence of these blind cave animals can be accounted for 
only by supposing that their remote ancestors began making excursions 
into the cave, and, finding it profitable, extended them, generation after 
generation, further in, undergoing the required adaptations little by lit- 
tle.’—Herbert Spencer, Popular Science Monthly, XLIII, 487 and 488. 
The first of these views is based on two facts, as everyone familiar 
with caves and their faunas will readily agree. These facts are, first, the 
author’s lack of knowledge about caves and his disregard of the nature of 
the animals inhabiting them. 
The second of these theories is more nearly applicable to the blind 
fishes. A partial adaptation to do without eyes is found in those species 
inhabiting the swamps of the Southern States. The eyes of Chologaster 
cornutus are very simple. In the species living under rocks and in caves, 
Ch. agassizii, there is a high development of the tactile organs, with a 
more perfect eye than in those living in the open. These fishes were 
adapted to do in part without light before they entered the caves an¢ 
before their eyes had become seriously degenerate. 
With the subsequent suppression of the eye in darkness natural selec- 
tion can not have operated, as Lankester supposed, for species of the 
Amblyopsidz with well-developed eyes still live in the caves by the side 
of those with mere vestiges of eyes. 
