6 gangetic fishes. Order I. 



which are small, are placed near the middle of the fish in re- 

 spect to height. 



The rays of all the fins, except the caudal, are so covered by 

 a thick skin, and are so small, that they are numbered with dif- 

 ficulty and uncertainty, so that a great expectation of accuracy 

 concerning the numbers stated should not be entertained. 

 All these species have small horizontal mouths with fleshy lips, 

 the vent behind the middle, and the gill aperture near the pec- 

 toral fins, and forming part of a circle. 



1st Species. — Tetrodon fluviatilis. Plate XXX. Fig. 1. 



A tetrodon with a body little compressed; with jaws of 

 nearly equal length, but the superior by a little the longer ; and 

 with the back dusky-green divided, by yellow lines, into angu- 

 lar spaces like the plots in a garden. 



This fish grows to about six inches in length, and is found in 

 the fresh water rivers of the lower parts of Bengal. On this 

 account it is called by the natives the river Patoka, to dis- 

 tinguish it from another found in ponds, and from another 

 found in estuaries, for the term Patoka is generic. 



This fish, as to form, when it inflates itself, has a moderately 

 projecting belly, somewhat shaped like an egg, and tapering 

 gradually to the tail. On the head, back, and belly, it is arm- 

 ed with small undivided prickles, which the animal can retract 

 into some large pores in its skin. With respect to colour, the 

 sides have large round spots, the lower parts are white. The 

 fins are dusky, with two dark transverse bars across that of the 

 tail. The eyes are yellow. When this fish has lived in dirty 

 water, its belly becomes black, and its fins yellow. 



The head slopes downward from the neck to the mouth, is 

 shaped like an egg, is large and wider than the body, and 

 ends bluntly. The ^"aw-bones do not protrude in opening. 



