THE TETRAODIN^j OR HARE-FISH. 



197 



matus Riipip., fig. SI.), have acquired this name from 

 the sharp edges of the jaws being divided in the middle. 



so as to present the appearance of four teeth — two above, 

 and two below ; and this structure also gives them a 

 remote analogy to the lips of the hare. The tail is 

 more lengthened than in any other of the cheloniform 

 fishes, in accordance with what we should expect in the 

 apodal type : the spines on the body are so short, that 

 they are mere prickles; while, in some, they merely 

 assume the appearance of rough asperities on the skin ; 

 the body is nevertheless, very slimy.* These fishes are 

 remarkable for having only three gills or branchia on 

 each side, — a structure which prepares the passage from 

 the BalistidcB to the ChironectidcB, where the number is 

 precisely the same. The rays of all the fins, except the 

 caudal, are covered by a thick skin ; and all the species 

 have small mouths with fleshy lips. The food of all 

 these small-mouthed fishes appears to be crabs and shell. 



Hamiltor.'s Gangetic Fishes, p. 5. 



3 



