400 INDIAN CYPRINID&. Sarcoborine 
Remarks 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 
Peonomine, and implies a totally different economy from what belongs to 
those Sarcoborine 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. 
