Apalopterincs. INDIAN CYPRINID^. 425 



The first sub-genus is peculiar to the rivers of America, the third 

 is only found in India, and the remainder are common to Europe and 

 America. 



The Platycarce, PI. 49, form the next genus ; in these the head is also 

 flat, with the eyes placed on the upper surface, as in the Siluridcs ; but the 

 mouth is small, without teeth, and soft. The alimentary canal is however 

 short, as in carnivorous species ; their pectorals are round, and sometimes 

 placed on fleshy pedicles or arms, with but two rays in the branchial mem- 

 brane. This remarkable genus corresponds with the natatorial type, to which 

 I conceive the Pcecilincs also belong, notwithstanding their small size. 



The Psilorhynchi follow the last in the order of their aflinities ; in these the 

 snout, rather than the head, is flattened, and much elongated in front of the 

 mouth, which is remarkably small. This genus connects the Loaches with the 

 Platycarce, and affords the suctorial type, as will be seen from the descriptions 

 (and figures, PL 50) of the only two species yet met with. 



To these last the Loaches follow. I have already stated my reasons for 

 having arranged them according to their colours and form of the caudal ; I shall 

 now merely notice one or two points on which their typical characters seem 

 to rest. In this group the suborbitar plates are transformed into spines, 

 which are fixed by an articulation to a process of the frontal bone in front of 

 the eye, so as to be raised at pleasure as organs of defence, like the horns of 

 Ruminants ; at other times these spines are lodged in a suborbitar sinus, si- 

 milar to that of the Cermdce. Of the two sub-genera into which I have divid- 

 ed them, the true Loaches, or those with the caudal entire, appear to be the 

 more terrestrial, in consequence of the rudimental character of the natatory 

 bladder, or, of its total absence in many of the species ; while in some 

 of the Scliisturce, or those with bifid caudal, there is an abdominal air-vessel 

 enabling the species possessed of it to frequent the deepest waters in the 

 lai'gest rivers, while the true Loaches are generally found in creeks and 



jeels, and would thus appear to present a closer relation to Apodal fishes ; 



3 H 



