FAMILY SILURID.E PIMELODUS. 185 



THE BLACK CATFISH. 



PlMELODUS ATRAHIUS. 

 PLATE XXXVI. FIG. 116. — (CABINET OF THE LYCEUM.) 



Characteristics. Black. Adipose dorsal long and slender ; the rays of the fins passing beyond 

 the membrane. Caudal emarginate, round, with numerous accessory rays. 

 Length four to eight inches. 



Description. Surface smooth and scaleless. Lateral line distinct, nearly straight, slightly 

 convex under the dorsal fin. Head depressed, sloping. The barbels, in number and arrange- 

 ment, resemble those of the preceding species. Lips fleshy, with minute punctures. Teeth 

 in the jaws minute, long, conical and crowded. Tongue smooth. Humeral bone with a long 

 concealed spine above the pectoral, and a short blunt rudimentary process directed downward 

 at the upper angle of the branchial aperture. 



The dorsal fin higher than long, arising midway between the pectorals and ventrals ; the 

 first ray an acute triangular spine ; its anterior surfaces marked with oblicme rugae or wrinkles ; 

 its anterior edge smooth ; a small accessory bone at its anterior base ; six soft rays, the first 

 and second longest. The adipose dorsal as far from the last rays of the first dorsal, as the 

 anterior ray of that fin is from the end of the snout ; long and slender, rounded, and laci- 

 niate at the tips. The pectoral fins nearly on the plane of the abdomen, and anterior to the 

 upper angle of the branchial aperture, containing one spinous and seven branched rays : the 

 spinous ray robust, triangular, slightly curved, with its anterior edge roughened, and its sides 

 channelled as in the spine of the first dorsal ; a small filamentous ray is connected with it, its 

 posterior edges with decurved spines ; the second, third and fourth rays somewhat longer 

 than the spines. Ventrals small and feeble, pointed, their tips scarcely reaching the third 

 anal ray ; the third and fourth rays longest. Anal fin long ; the first four successively longer, 

 when they become subequal to the last four or five rays, when they gradually diminish in 

 length. Caudal slightly emarginate, rounded at the tips. 



Color. Deep black, occasionally blackish brown above and on the sides ; ashen grey beneath. 



Length, 4' 5. 



Fin rays, D. 1.6.0; P. 1.7; V. 8; A. 20; C. 17f. 



This species occurs commonly in Wappinger's creek, a tributary of the Hudson, Dutchess 

 county. They occasionally occur there of dimensions larger than those given above. 



In concluding the history of the Siluridaa observed in the State of New-York, I must call 

 the attention of our ichthyologists to a species which has been rather indicated than described 

 by Dr. Mitchill in the American Monthly Magazine for 1818. If there be no error in the 

 description, it will form the type of a new genus in this family, already so rich in the variety 

 of its forms. It approaches the Silurus of Cuvier and Valenciennes, of which they observe, 



Fauna — Part 4. 24 



