360 CLASSIFICATION OF FISHES. 



ramified branchia, it is even a more extraordinary de- 

 viation from the usual form than that of Syngnatkus ; 

 so thatj if the latter genus deserves to be placed as a 

 distinct di^dsion of the osseous fishes, according to 

 Cuvier's system, Heterohranchus should form a third. 

 We belieTCj ho^vever, that this variation in the bran- 

 chia is not simply confined to one type only of the 

 Siluridce., but to several ; at least, the fishes that are 

 said by Cuvier, Geoifroy, and Spix to possess these 

 ramified branchia, are widely different in nearly all 

 other parts of their structure. It is, in short, by this 

 means, that nature indicates the analogy -which the 

 aberrant Siluridce^ as a whole, bear to the amphibian 

 sirens, which they represent; just in the same manner as 

 the genus Cinclus among perching birds, by its aquatic 

 or amphibious habits, represents the grallatorial order. 

 To make this circumstance a reason for arranging 

 Cinclus as a primary division of the perching birds, 

 would appear to us as great a violation of nature as 

 that of making SyngnatJius, and all these Heterohrancliia, 

 types of distinct di^isions in the osseous fishes. 



(■SOI.) The family of the Cobitid^, or loaches, 

 have the gi'eatest affinity to the last, near to which all 

 ichthyologists have placed them. Like the silures, 

 they are fluviatile fish, generally lurking close to the 

 ground ; and they probably feed in the same way, for 

 the mouth is generally furnished vsdtli barbels, and the 

 body is slimy. In all other respects, however, they 

 materially differ, both from the SiluridcE and the 

 CyprincE, or carps, in their structure, but more especially 

 in their mode of propagation ; for they are aU vivi- 

 parous, Hke the cartilaginous fishes, and thus stand alone 

 among the malacopterygious families, as presenting 

 almost a solitary exception * to the oviparous nature of 

 all the others. The analysis we have given of the 

 SiluridcB demonstrates that this remarkable group does 



* Some of the SiluridcB are stated to be also viviparous ; but we know too 



little of these fishes to sanction the belief that this mode of propagation is 

 general among the great majority of the genera. 



