210 
U. S. 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. 
Catal. 
No. 
No. of 
spec. 
Age. 
Locality. 
When collected 
Whence obtained. 
Orig. 
No. 
Nature of 
specimen. 
Collected by— 
923 
i 
Adult. 
Near San Antonio, Tex. 
1853 
Lt. A. W. Whipple. 
10 
Alcoholic. 
Dr. C. B. Kennedy... 
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 ; C 7, 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 XLIA", 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. 
Catal. 
No. of 
Age. 
Locality. 
When collected 
Whence obtained. 
Nature of 
Collected by— 
No. 
spec. 
specimens. 
904 
i 
Adult. 
Lake Amelia, near Fort Snelling, 
1853 
Gov. I. I. Stevens.. 
Alcoholic. 
Dr. Geo. Suckley. 
Minnesota. 
905 
i 
1853 
1 
