120 ICHTHYOLOGIA OHIENSIS 



Pectoral fins commonly armed. Teeth like a file. 

 Vent commonly posterior. 



The extensive genus Silurus of Linneus, which is 

 scattered throughout the rivers of both continents, 

 has not yet been completely illustrated, notwith- 

 standing the labours of the modern ichthyologists. I 

 have found in the Ohio about twelve species belong- 

 ing to it : most of which offer consimilar characters 

 and appear to belong to the genus Pimelodus of Lace- 

 pede and Cuvier : which have left the name of Silurus 

 to the species having one dorsal fin. I have already 

 published a monography of them in the Journal of 

 the Royal Institution of London, under the generic 

 name of Silurus. I now propose to form with them 

 a peculiar subgenus, divided in many sections, and 

 different from the subgenera Bagrus, Synodontus, Silu- 

 sox, &c. 



[II. 356] Subgenus. Ictalurus. 



Head depressed with eight barbs, one at each cor- 

 ner of the mouth, longer than the others, four under 

 the chin, and two on the snout behind the nostrils. 

 Teeth in two patches, acute and file-shaped. Pec- 

 toral fins and first dorsal fin armed with an anterior 

 spine. First dorsal trapezoidal and before the ab- 

 domi- [62] nals, second opposite the anal. Body 

 compressed behind, vent posterior or sub medial. 

 Operculum simple. 



The fishes belonging to this group are common 

 throughout the United States, the Silurus catus of 

 Linneus, which is not found in the Ohio, belongs 

 also to it. They are sedentary in the Ohio and 

 branches, and very voracious, feeding on all smaller 

 fishes: they are easily taken with the hook; their 

 flesh is esteemed, and, although it is somewhat tough 



