368 INDIAN CYPRINIDiE. Fceonomince . 



Some of the Gudgeons might from the situation of the mouth be describ- 

 ed as Gonorhynchs ; the latter differ from the former chiefly in having the 

 lower jaw formed for uprooting a scanty food derived from plants that are 

 fixed, rather than for merely collecting such as are loose and floating plenti- 

 fully throughout the waters they inhabit. The two groups have therefore the 

 nearest affinities to each other, the nature of the food, and the structure of 

 the digestive organs being nearly the same in both. The difference between 

 them arises rather from the circumstances in which they are respectively 

 placed, than from any thing peculiar to the nature of either, that the other does 

 not possess ; and may be traced perhaps to an easy existence on the one hand, 

 in the still waters of ponds and lakes, amidst abundance of food derived from 

 loose, floating vegetation ; and, on the other, to the precarious struggle for 

 life in mountain torrents, liable to sudden and violent floods, which as sudden- 

 ly subside. These conditions seem to allow of the weak jaws, clumsy bodies, 

 and feeble fins of the Gudgeons ; and to require in the Gonorhynchs a struc- 

 ture more adapted to battle against the difficulties of their situation in the cold 

 rocky streams of high altitudes, where aquatic vegetation is scanty, and only 

 to be obtained by force from the slippery surface of boulders, and water- worn 

 rocks. The most remarkable character which belongs to the group, is a cir- 

 cular disk or sucker, which is placed on the lower surface of the head, behind 

 the lower jaw. This is no doubt used in cases of difficulty for adhering to 

 rocks, and thus resisting the violence of mountain torrents which, without 

 such a contrivance they would be unable to withstand. This character, no 

 less than the inferior position and structure of the mouth, seems to indicate a 

 relation with the Palatycara, Lampreys, and Cyclopterus. Their fins are 

 strong, but not large, and the rays are soft, and often enclosed in a thick 

 membrane : their bodies are elongated, by which they are rendered more 

 manageable in rapid currents, while the peculiar structure of the lower 

 jaw affords an instrument singularly adapted for obtaining the only 

 food procurable in the rocky basins to which they are confined. These 



