236 CLASSIFICATION OF FISHES. 



simple rays^ and of little flexibility. Raniceps^ among 

 iJie Gadidce, is a still^more striking prototype of the 

 common Lophius piscatorius, or fishing frog; an analogy 

 so obvious as to be conveyed by their respective names. 

 The mailed SiluridcE, forming the typical LoricarincE, 

 find their representatives among the cheloniform fishes^ 

 in the singular families of Syngnathus and Pegassus, 

 Nor does their analogy rest alone on their external ana- 

 tomy. Cuvier^ as we have already shown, has separated 

 the Sygnatliidce from all other fish, on account of their 

 branchia assuming the form of tufts ; and yet, although 

 he is perfectly aware that the very same deviation from 

 the ordinary branchia of fishes is found in another 

 group, he merely considers the latter as only deserving 

 of a simple generic distinction. The genus we allude 

 to is that of Heterobranchus of Geoffrey Saint- Hilaire, 

 which, in addition to the ordinary branchia, have 

 others attached to them, resembhng tufts, considerably 

 ramified ; so that these fishes combine the branchia of 

 two distinct classes, namely, that of Pisces and of Am- 

 phibia. Among fish, their only prototypes, in this 

 respect, are the Syngnathidce, w^hich, as we have already 

 shown, are also the representatives of the amphibious 

 reptiles. If primary divisions are to be made on such 

 apparently anomalous characters, Heterohranchus has 

 precisely the same claim for such a distinction as Syng- 

 nathus : but the fact seems to be, that this structure, far 

 from being anomalous, is what we should expect in groups 

 that stand at the greatest distance from their respective 

 types ; and from its thus occurring both in the Syngna- 

 thidce and the Siluridce, we discover that it is in perfect 

 harmony with the usual course of natural variation, — a 

 variation which frequently makes one group represent 

 another in the most unexpected and singular manner. 

 The cartilaginous type of the cheloniform fishes, if not 

 Polypterus, appears to be undiscovered ; and this may 

 account for there being no group in that order which 

 represents the Cohitidce, which form the cartilaginous 

 type in the circle of the Mahcopteryges. 



