10 PISCES. 



nection with each other as those of man have ; for 

 their eyes are not placed in the fore-part, but in the 

 sides of the head , and consequently cannot look so 

 conveniently at any object with both eyes at the 

 same time. 



The crystalline lens in Fishes is a complete sphere, 

 and more dense than in terrestrial animals, that the 

 rays of light coming from the water might be suffi- 

 ciently refracted. 



As Fishes are continually exposed to injuries in 

 the uncertain element in which they reside, and as 

 they are in perpetual danger of becoming a prey 

 to the larger ones, it was necessary that their eyes 

 should never be shut; and as the cornea is suffi- 

 ciently washed by the element they live in, they are 

 not provided with palpebrse : but, as in the current 

 itself the eye must be exposed to several injuries, 

 there was a necessity that it should be sufficiently 

 defended ; which, in effect, it is, by a firm, pellucid 

 membrane, seeming to be a continuation of the 

 cuticula stretched over it : the epidermis is very 

 proper for this purpose, as being insensible, and 

 destitute of vessels, and consequently not liable to 

 obstructions, and thus becoming opake. In the eye 

 of the skate tribe there is a digitated curtain which 

 hangs over the pupil, and which may shut out the 

 light when the animal rests, being somewhat similar 

 to the tunica adnata of other animals. 



Although it was formerly much doubted whether 

 Fishes possessed the sense of hearing, yet there can 

 be little doubt of it now ; since it is found that they 

 have a complete organ of hearing as well as other 



