INDIAN CYPRINIDE. 24) 
necessary to recollect that the herbivorous Cyprins are characterised by their 
plain colours and great length of intestinal canal, which varies from six to 
twelve lengths of the body in the different groups; those with the shortest 
(the Barbels) intestine being in the centre of the sub-family, it follows that 
the two extremes must meet, or shew a tendency to approximate or close. 
The herbivorous Carps are united to the Sarcoborine by means of the 
Gonorhynchs and Systoms, and shew like the last a tendency to form a circle 
of themselves, though it is probable that the group is yet far from being 
complete. The Sarcoborine and the Loaches are united by two new types, 
the Platycara and Psilorhynchus ; and the Schistura in addition to approxima- 
ting to the Platycura unites, or shews a tendency to unite both in form and 
habits with the Peonomine, the group with which we set out; thus exempli- 
fying the first principle of natural classification, namely, that every natural 
series of beings in its progress from a given point, either actually returns, 
or evinces a tendency to return again to that point, thereby forming a 
circle:* 
41. The second test of a natural group relates to the number of its 
types. On this point there exists some difference of opinion among 
writers on the natural system, which their profound inquiries are now 
doing much to remove. It is a question which, to understand sufficiently 
for practical purposes, requires an extensive knowledge of natural history, 
and a mind somewhat more imbued with the spirit of philosophy than has 
hitherto been considered requisite in those who ventured to name new 
genera. It has already been said that the lower jaw of the Labeos agrees 
with that of the Cirrhins, in being formed of two bones articulated behind 
to the anterior process of the preoperculum, and that in front a transverse 
* Swain. Nat. Class. and Geog. Dist. Anim. 224. 
