XXXII 
CONVERGENCE IN EVOLUTION 
N the darkness of the Deep Sea there are 
certain fishes whose eyes have dwindled to 
a vanishing-point. By means of delicate tactile 
organs they feel their way about on the sea floor. 
There are other ‘abyssal fishes with enormously 
enlarged eyes, and it is reasonably supposed that 
they are able to profit by the faint illumination 
due to “ phosphorescent’ deep-sea animals. Yet a 
third condition is seen in a number of fishes from 
great depths in which the eyes are elongated into 
cylinders, projecting like opera-glasses on the top 
of the head. These have been called “ telescope 
eyes,” and they are adapted to make the most of 
faint light. The lens is relatively large, and the 
distance between it and the surface of the retina, on 
which the image is formed, is much greater than 
usual. Something of the same sort is seen in the 
eyes of owls, though they do not project in the same 
way. For the sake of simplicity let us leave the 
owls and two or three similar instances out of 
account, and focus attention on the fact that the 
“telescope eyes” of some deep-sea fishes are 
closely paralleled by “telescope eyes” in some 
deep-sea cuttlefishes, which, of course, are mollusks. 
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