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VERTEBRATA 



to the vast numbers caught. A few species of salmon 

 inhabit the streams along the north Atlantic coast. 



The trout are the most delicious of all the food fishes. 

 Of these the brook trout (Salvelinus fontinalis), orna- 



Fio. 222. The brook trout. Photograph one third natural size. 



men ted with red spots, is the most famous. It inhabits 

 the cold streams from Maine to Dakota, and is often culti- 

 vated in ponds. Owing to insufficient protection by law, 

 the supply is becoming limited. 



The cave fishes are represented by several species in this 

 country, dwelling in subterranean streams. Those living 



PIG. 223. Photograph of the common mackerel one third natural size. 



in the Mammoth Cave of Kentucky are white and entirely 

 blind. Their ancestors possessed eyes, but lack of use 

 throughout many generations resulted in blindness. Quite 

 as remarkable as the cave fish are the flying fish of the ocean. 

 They dart obliquely out of the ocean and spread the broad 



