THE TRUE FISHES. 



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unparalleled voracity. Everything in the water is food for them. I 

 will swallow snakes and frogs, and even the swift troul often fui 

 them a meal. Fishing for pickerel is exciting sport . In the bright, 

 days of autumn the fisherman goes to the lake or some still rea< h 

 river, and trolls his spoon-hook through the lily-pads. The] 

 gleam in the water, a sudden dash, and a pickerel is hooked. 



A few of the relatives of the pike and pickerel musl be menl 

 Among them is the mud-minnow of the northern small 



which delights in muddy and swampy 

 streams, but is not of the slightest eco- 

 nomical importance. A South Amer- 

 ican ally, Anableps, is far more inter- 

 esting from the peculiar structure of 

 its eyes. It swims at the surface of 

 tropical streams, with part of its head 

 above and part below the water, and its eyes are divided into two p 

 one being fitted for vision in the air, the other being like that of ordin 

 fishes. Corresponding to this double eye are two pupils, ami the lei 

 have different curvatures in the two part-. These fish attain ,1 length 

 about a foot. 



The blind-fishes also are interesting, but in this case the interest cenl 

 in the rudimentary condition of the eyes. Five species are known, but I 

 most celebrated is the form which lives in Mammoth and Wyandotte 

 while others are found in Cuba, and in the streams running through 

 rice-fields of the south. In these but the rudiments of the eye ind 



Fig. 306.— Mud-minnow i /'/„'. 



Fig. 307. — Bliud-fish of Mammoth Cave {Arab 



the optic nerve, usually so well developed, is reduced to a n 

 Living as they do in subterranean streams, eyes are if no use 

 In the perfect darkness which exists in the underground 

 strongest of eyes could distinguish nothing, and so nature v. 

 in preserving an organ absolutely useless. Their sense of hea 

 other hand, is acutely developed, and it is as difficult tch 



of their relatives with eyes. " It requires the greatest caution to 1 



