Sight 307 



near-sighted fish, and limit their range of vision 

 to eight or ten yards. If this be so, and it is a 

 very close estimate, open to dispute, the trout has 

 much weaker eyes than the black bass, which I 

 have seen come to my flies from a distance of at 

 least forty-five feet, making a plainly discernible 

 wake across a shallow reach of the river. The eye 

 of the trout is, doubtless, well adapted to the ele- 

 ment in which it lives. It has no eyelids, but, in 

 lieu of them, the skin of the head passes over 

 the eye and becomes transparent. The cornea, 

 the admitter of light, is flat, not convex as in the 

 higher animals, — a wise provision of nature for 

 the protection of the eye in the battle for life 

 waged at all times among fishes. The reflective 

 apparatus of the eyeball of a fish, as in land ani- 

 mals, is the lens, which is of considerable density 

 and size. It is a powerful agent in reflecting the 

 rays of light, and were it not for the density of 

 the medium in which it lives, the trout would 

 doubtless be gifted with acute vision at long 

 range ; but the power of the eye in fishes can 

 only be imperfectly estimated by observation of 

 their actions from the banks of a stream or other 

 places ; it can only be conjectured as to what 

 effect the water, as a medium, has upon the organ 



