400 



INDIAN CYPRINID^. 



SarcohorincB 



RemarJis on the Genus. 



The lengthened rays of the pectoral and ventral fins of Perilampus perseus, 

 together with the broad surface of the anal, enable it to move along the surface 

 of the water in pursuit of flies and other insects, — a mode of life for which every 

 part of its structure is admirably formed. The mouth, as already stated, is 

 so constructed as to be carried above the surface, even when other parts of the 

 body are submersed. This essential peculiarity of a species that derives its 

 subsistence exclusively from an element superincumbent to that which it 

 inhabits is effected by means of the lower jaw, which instead of being horizon- 

 tal, or even slightly inclined, is placed almost vertically in front of the mouth, 

 so that the apex of the jaws are higher than any other part of the body, and 

 diametrically opposite to what obtains in the ground-feeders, or typical 

 Pceonomince, and implies a totally different economy from what belongs to 

 those SarcoborincB that derive their food from within their own element. 

 In these last, as we shall see in the genus Opsarius, or fish-eaters, the mouth 

 is wide, unencumbered with a tongue, and extended straight forward. A 

 tongue indeed to animals that swallow living prey approaching in an incredible 

 degree to their own size, would be an useless appendage. The mouth of 

 the Opsarions is therefore to be regarded as little more than a prehensile 

 apparatus, equivalent to the claws and hands of other animals ; but in the 

 fly-catchers, or Perilamps, the mouth is furnished with a large rugose, and we 

 may presume highly sensible, tongue, which is requisite for conveying into 

 the stomach minute objects that would otherwise adhere to the sides of the 

 mouth. 



In none of the Barbels, Cirrhins, or Gudgeons, nor in any of those groups 

 that live on plants, shell fish, or other objects obtained by scraping or rooting 

 in mud, do we find any thing like a soft or sensible tongue, the office of which 

 is in many cases better performed by cirri. 



