230 INDIAN CYPRINID#. 
other Sarcoborine. As we advance in this sub-family from the Systoms towards 
the Opsarions, we find as has been shewn, the abdominal tube diminishing 
in length, and in proportion as this takes place, and the habits of species 
become more carnivorous, we observe the brilliancy of the colours becomes 
more remarkable. 
22. The Perilamps, as already stated, are followed by the Leucises. In 
these the diversity of colour is not great, but is compensated for by the 
metallic brilliancy of the nacre, or silvery pigment with which the scales 
and opercula are covered, and from which the genus has derived its name 
Leuciseus, Ables, or white fishes, though not applicable to all the species; 
for there is one which is marked on each side with the bright longitudinal 
streak of the Perilamps, and like the blending of the markings already 
observed between the Peonomine and Sarcoborine the species in ques- 
tion, Leuciscus lateralis,* seems to unite the white fishes with the Perilamps. 
23. The Perilamps in their structure naturally follow the Systoms, and 
present numerous bright longitudinal lines of various colours, but particularly 
blue on their sides. They are all small species of little or no direct utility to 
man, nor is it possible to account for the peculiar brillianey of their colours in 
any other way than as an instance of that inscrutable design, by which it 
would seem that in pursuit of aquatic insects on which they subsist along 
the surface of waters, they become the better marks for Kingfishers, Skimmers, 
Tern, and other birds which are destined to keep the number of fishes in 
check, especially in deep waters beyond the reach of the waders.+ 
* Cyp. Daniconius. Buch. which appears to me to be identical with Cyp. Anjano, id. ; but if 
not, the latter species on account of certain peculiarities about the mouth, which seem to be 
wanting in the former, must be referred to the Perilamps. 
+ See remarks on P. perseus in a subsequent part of this paper. 
