354 CLASSIFICATION OF FISHES. 



together ; in which respect, notwithstanding the essen- 

 tial differences of their structure, he is closely followed 

 by Cuvier. We now come to Pusichthys : when we look 

 to the small and nearly vertical mouth, we at once see an 

 exemplification of those peculiarities by which Urano- 

 scopus, and all chironectiform types are so singularly 

 distinguished ; this, in fact, is the only sub-genus of the 

 above group that has the mouth opening vertically, while, 

 by the turning up of the snout, it preserves a resemblance 

 to Malapturus. The analogy of Clupisoma to Agenio- 

 sus (or, rather, to its type, the sub-genus Silonia) is very 

 striking ; the exceeding long cirri of Clupisoma and its 

 single dorsal fin, at once show its affinity to Silurus ; 

 and yet, setting these peculiarities aside, Clupisoma and 

 Silonia are so like each other, and yet so different from 

 all their congeners, that they appear almost related by 

 affinity. Clupisoma has the same compressed head and 

 body, the same fulness of the eyes, the same sharpness 

 on the edge of the belly, the same semi-transparent sides, 

 &c., as we see in Silonia; yet it has but a single dorsal 

 fin : we are at no loss to recognise, in both, a type of the 

 Gymnetres, or riband-fish. Further comment upon these 

 analogies would be superfluous. We now return to 

 the affinities of the remaining sub-families. 



(288.) The fourth principal division of the Siluridts 

 is that of the Aspredince; the typical distinctions of 

 which are as follows : not only the head, but the ante- 

 rior part of the body, is considerably flattened, while the 

 tail preserves some resemblance to that of the last sub- 

 family, the Siliirince, in being generally slender ; the eyes 

 are remarkably small, and placed on the crown of the 

 head, so as to become vertical ; the branchial aperture 

 is spiraculated, as in the cheloniforra fishes, and consists 

 of merely a slit of the skin ; while the operculum itself, 

 '' unlike," as Cuvier observes, " all other osseous fishes, 

 is immovable." These are the positive characters of 

 these singular fishes; but in other respects they vary 

 considerably. In our new genus Cotylephorus (C. Blochii, 

 fig. 90.), which connects these to the SilurincB, the anal 



