THE COMMON DOG-FISH. 



195 



at the end, whereas in the former they are of a diamond-like form. The color of the Rock 

 Dog-fish is brownish-gray above, without the red tinge of the little dog-fish, and covered rather 

 sparingly with large patches of blackish-brown. Below it is whitish. The length of a fine 

 specimen will sometimes be nearly a yard. 



Another species of Dog-fish, namely, the Black-mouthed Dog-fish, or the Eyed Dog- 

 fish {Pristidurus melanostomus), is mentioned by Mr. Yarrell among the list of European 

 fishes. It may be at once distinguished from either of the preceding species by its large snout, 

 and a row of small, fiat, and sharp-edged prickles, arranged in saw-like fashion on the upper 

 rim of the tail fin. The generic title Pristidurus, or Saw-tail, is given to the fish in allusion 

 to this peculiarity. 



Its color is light brown on the upper surface, sprinkled with spots, the smaller of which 

 are scattered irregularly, and the larger arranged in four rows, two on each side. 



Its length is between two and three feet. 



■MTOMjg Wn ii. 



ROCK DOG-FISH. — Scyllium catulus. 



The Dog-fish family includes six or more genera. The species number fifteen, — rather 

 small sharks, chiefly of the Atlantic. The Black Dog-fishes are represented by one species, 

 found lately off Gloucester, Massachusetts, by the naturalists of the United States Fishery 

 Commission. It is a native in the Greenland seas. 



The Common Dog-fish, or Picked or Piked Dog-fish ; also called Bone-dog, from 

 its potent bony weapons ; also Skittle-dog, and Hoe. Its range in the Atlantic is very 

 wide, being very abundant on the shores of the Northern and Middle States. Its oil, from the 

 liver, is prized, and it forms an important item of commerce among the lisliei men. 



