FISHES—SILURIDAE—PIMELODUS OLIVACEUS. 
211 
5. PIMELODUS LUPUS, Grd. 
Spec. Char. —Body subfusiform, compressed ; head depressed, broader than deep, anteriorly tapering', and constituting the 
fourth of the total length. Mouth moderate size, upper jaw the longest. Maxillar barbel extending to about the middle of 
the pectoral fin. Eye sub elliptical, of medium size, its diameter entering nearly seven times in the length of the side of the 
head, and about three times in the interocular space. Dorsal spine very obtusely denticulated towards its upper extremity; 
pectoral spine very conspicuously so. Caudal fin moderately furcated. Base of anal fin shorter than the head, and contained 
nearly five times in the total length. Blackish brown above, dull white or light slate colored beneath. 
This species resembles somewhat P. vulpes (figured in the Rep. to the U. S. and Mexican 
Boundary Commission) in its general physiognomy, differing, however, from the latter by a 
proportionally shorter head. It belongs to that division of the genus in which the body and 
head assume a rather slender appearance. It is, however, more compactly built than most of 
its allies. The rays of the fins are : 
Br. YII: YII; D I, 6 ; A 24 ; C 10, 1, 8, 7, 1, 10; V 8 ; P I, 9. 
The insertion of the ventrals is nearly equidistant between the extremity of the snout and the 
insertion of the caudal. These fins themselves are broad, overlapping the vent and reaching the 
anterior margin of the anal when stretched backwards alongside the abdomen. The nasal 
barbels are slender, and do not extend as far as the posterior rim of the orbit. 
The upper region is dark brown with a metallic reflect, the head beneath being dull white and 
the abdomen light bluish or slate colored. 
List of specimens. 
Catal. 
No. 
No. of 
specs. 
Age. 
Locality. 
When collected 
Whence obtained 
Nature of spec. 
Collected by— 
915 
i 
Young . 
From Indianola to Nueces_ 
1854 
Capt. John Pope. 
Alcoholic.__ 
Capt. Pope_ 
916 
3 
Adult.. 
Head waters of the Rio Pecos. 
1854 
6. PIMELODUS OLIYACEUS, Grd. 
Plate XLI, Figs. 1—3 ; and Plate XLII. 
Spec. Char. —Body sub-fusiform, compressed. Head very much depressed and tapering, constituting about the fifth of t' a 
whole length. Mouth small; upper jaw the longest. Maxillar barbel extending to the middle of the pectoral fin. Eye large, 
sub-elliptical ; its diameter contained five times and a half in the length of side of head, and about twice on the interocular 
space. Dorsal spine very finely serrated posteriorly; pectoral spine very strongly so. Caudal fin deeply furcated. Olive- 
brown above ; olive-white beneath. 
The body and head have a rather slender appearance. It is allied to P. ccelurescens , from 
which it appears to differ by several minor characters, which we must refrain for the present to 
express comparatively in words, not having before us the specimens of the typical P . ccerulescens, 
preserved in the museum of the Smithsonian Institution, but not available at the time these 
pages were passing through the press. We have counted the rays upon specimens from the 
Yellowstone river, and found them to be as follow : 
Br. YII: YII; D I, 6 ; A 26 ; C 10, 1, 8, 7, 1, 9 ; Y 8 ; P I, 8. 
The nasal barbel is slender and rather short, and when stretched along the surface of the 
bead not extending as far posteriorly as the hinder rim of the orbit, but averaging about 
between the latter and the pupil. 
