009 
long tactile hairs, like those of the blind Centipede (Spirostrephon) 
in the Mammoth Cave ; or of fleshy processes on the head, lower 
jaw, or fins of many fish. 
The action of Natural Selection on animals migi-ating into caves, 
or penetrating into the deeper abysses of the ocean, has doubtless 
tended to perpetuate, first individuals, and then races with abnormally 
large eyes ; or else by favouring those, which, from the possession of 
tactile organs, or from some other cause, have been able to exist 
without light, has produced forms to which light is perfectly 
useless, which forms have in many cases lost the function of their 
eyes, and often the eyes themselves. But in company with these 
two groujis wo meet with animals but little departing from the 
normal in the structure of their eyes, of which they can make 
little or no use. 
Much has still to bo done in the investigation of the mode of 
life of deep-sea and cave animals, and of the inliuences to which 
they are exposed, and such inquiry can hardly fail to be attended 
with results alike interesting and important to science. 
