Perilampus. INDIAN CYPRINIDZ. 389 
that author of much of the merit to which his labours as a naturalist en- 
titled him, but the world at large of the masterly elucidation of this subject 
that might have been expected from the hand of Cuvier. 
Notwithstanding the very general assemblage of forms that Cuvier’s 
definition of the genus Adbramis might be supposed to admit, the European 
species only amount to five, and three of these are peculiar to the tributaries 
of the Baltic. I found, however, upon a close examination of Indian Cypri- 
nide that if we were to content ourselves with the characters given of the 
Breams by systematic writers, we should not only confound at least two 
natural groups, but augment our Indian species of that genus to about 
thirty five in number. 
From this vast accession of materials, for which we are chiefly indebted 
to Buchanan, I am enabled to distinguish two natural genera, Perilampus and 
Opsarius, and to suggest something like natural limits to the hitherto ill 
defined genus Leuciscus. Before entering upon the consideration of any 
one of these groups, it is necessary to offer a few remarks on their general 
' distinctions. 
The Perilamps, so called from the brilliancy and variety of their colours, 
as well as the Opsarions, or fish-eaters, seize their prey by means of a sudden 
effort or spring, for the performance of which the great breadth of fin appears 
to be accumulated behind. The mouth is armed with a prominent knob 
on the apex of the lower jaw, more or less sharp in the several species; when 
the mouth is closed this knob is received into a corresponding fissure in 
the upper jaw: thus far the two groups agree, but in the general develop- 
ment of their forms and structure, nature has assigned to each a totally 
distinet organization, adapted to the peculiar ends for which the species were 
designed. Between the two groups here alluded to the Lewcisct occur, con- 
sisting perhaps of species that might be referred on the one side to the 
Perilamps, and on the other to Opsarions, rather than forming, by any distinct 
structure or habits of their own, a natural group. 
LOO 
