250 STRONG-TOOTHED HYDROCYON. 



ditto, webbed with blue ; ventral, greenish white ; 

 anal, green tipped with red; caudal, green tip- 

 ped with red and a broad bar of black; over the 

 opercle is a black spot, and at the sub-opercle ano- 

 ther. The maxillary bone is strongly toothed ; the 

 bones of the gill-lid are all striated ; the eye large 

 and yellow, placed before the middle of the head ; 

 scaling middle-sized, adhesive; ventral fins under 

 the commencement of dorsal ; nostrils single, oval, 

 close to the eye ; mouth terminal, gape large ; teeth 

 in a single row, spare canine teeth lying flat in the 

 mouth to supply again in case of breakage, like the 

 fangs of poisonous snakes. It lives a short time 

 only when taken out of the water, is good food, but 

 bony, takes bait readily, and preys on smaller fish, 

 which it swallows whole." 



D. 12_P. 8— V. 9— A. 19_C. 24_Br. 5_Vert. 48. 



In some of the specimens belonging to the genera 

 Serrasalmo and Tetragonopterus we saw species 

 reminding us, by their form, of the deeper shaped 

 carps ; in the fish we have next to describe, we see 

 another resembling the ordinary form of the chub 

 and roach, covered with large scales, having the 

 mouth, though armed with teeth, protruding, and 

 having the second dorsal fin almost rudimentary. 

 They are also vegetable eaters, but their habits 

 in other respects are too little known to allow us 

 to deduce from them any afiinity. Agassiz has 

 characterised them, from the cut margins of their 

 teeth, under the name of 



