210 



U. 8. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



This species belongs to that division of the genus in which the body assumes a rather short 

 and contracted appearance as well as the head. It reminds us of P. catus, P. catulus, and P. 

 felinus, and such like. The nasal barbel is proportionally long and slender, extending 

 considerably beyond the orbit. The external pair of submaxillar barbels is much longer than 

 the inner pair, and stretches considerably beyond the gill apertures. The anal fin is quite 

 elongated and rounded or convex upon its external margin. The rays are as follows : 



Br. VIII : VIII ; D I, 6 ; A 26 ; C 8, 1, 8, 8, 1, 7 ; V 8 ; P I, 9. 



The specimen before us measures about seven inches in total length, and an inch and a half 

 as its greatest depth. It is of a uniform reddish brown above, and of a dull white beneath. 



List of specimens. 



4. PIMELODUS AILURUS, Grd. 

 PLATE XLIV. 



SPEC. CHAR Head large, broad and depressed, constituting the fourth of the total length. Mouth large and wide ; lower 

 jaw the longest; maxillar barbel extending somewhat beyond the edge of the gill aperture. Eye small and sub-elliptical. 

 Dorsal and pectoral fins interiorly serrated. Base of anal fin entering about five times and a half in the total length. Caudal 

 fin somewhat emarginated posteriorly. Dark reddish brown above ; whitish beneath. 



This species is rather stoutly built, having a large head, thick and contracted body. It is 

 somewhat related to P. coenosus, differing from it by a larger head and an emarginated caudal 

 fin. The lower jaw, which protrudes beyond the upper one, appears also to be a distinguishing 

 feature between the two species. The nasal barbel stretches somewhat beyond the orbit when 

 laid over the head. The insertion of the ventral fins is equidistant between the tip of the snout 

 and the insertion of the caudal fin. The base of the adipose fin is placed opposite the posterior 

 half of the anal. 



Br. IX : IX ; D I, 6 ; A 22 ; T, 1, 8, 7, 1, 8 ; V 8 ; P I, 8. 



The upper region of the head and body is of a dark reddish brown, sometimes almost black, 

 whilst the inferior region is pale white, sometimes of a dirty yellowish. 



References to the figures. Plate XLIV, fig. 1, represents Pimelodus ailurus, somewhat 

 reduced in size. Fig. 2, being an outline of a view from above. Fig. 3, exhibiting the under 

 surface of the head. 



List of specimens. 



