Leuciscus. INDIAN CYPRINID 2. 403 
The effect of the foregoing definition, the substance of which may be ex- 
pressed in a few words, as in the synopsis, is to exclude Cyp. boga, Buch. 
Cyp. ariza, id. Cyp. sophore, id. ang Cyp. danrica, id. from this genus, though 
referred to in the Regne Animal as Leucisc?. The two first are Gudgeons, the 
third is a Systomus, and the fourth is a Perilamp, thus reducing the seven 
Indian species of this genus indicated by Cuvier to three. But in place of those 
removed we must add Cyp. cocsa, Buch. as its alimentary canal scarcely 
exceeds the length of the body, while that of the Barbels, with which it stands 
in the Regne Animal, varies from three to six times that length; it is besides 
without the dorsal spine of the Barbels, while it has faint bars across the body, 
indicating an approach from the Leucisci to the Opsarions. Six other species, 
most of which I have carefully examined, must also be added, making the 
number of our Indian Leue?sci already known amount to ten. 
The improvement, if there be any in this restriction of a genus acknow- 
ledged before to be imperfect, must rest a good deal on the principle, that 
nature in fixing the position of the dorsal fin, determines from this, what shall 
be the concurrent habit and structure of the species. 
In looking over the descriptions of the six European Leucises whose 
dorsal is opposite to the ventrals, we find the anal small, and the mouth low 
and horizontal, as if exclusively formed for obtaining their food from the 
bottoms of*waters, and we know this to be further confirmed by the fact of 
their subsisting chiefly on herbage and worms. We then arrive at Cuvier’s 
second division of this genus, in which the dorsal is placed behind the ventrals. 
Now, when the dorsal is placed so far behind the ventrals as to be opposite to 
the anal, I no longer regard the species as Leucises, but Perilamps or Opsari- 
ons, according as they correspond in most respects with one or other of those 
genera. If we take the Rudd (L. erythropthalmus) as an example, we find it 
is marked by the receded position of the dorsal, the greater development of 
the anal, the upturned mouth, and the remarkable brilliancy of colours, all 
denoting an affinity to the Perilamps; which is further confirmed by a cor- 
