208 
U. S. P. R. R EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
developed in the same proportions, with a caudal fin rounded, truncated, or sub-truncated ; on 
the other hand the body is slender and elongated, the head assuming the same appearance, the 
caudal fin being more or less deeply furcated. Pimelodus catus would typify the first division, 
and Pimelodus furcatus the second division. 
1. PIMELODUS CATULUS, Grd. 
Plate XLI, Figs. 4—6. 
Spec. Char. —Head very much depressed, constituting a little less than the fourth of the total length. Jaws equal; mouth 
of medium size. Eye rather small, sub-circular; its diameter entering about six and a half times in the length of the side of the 
head, and four times over the interocular space. The base of the anal enters five times in the total length. Caudal poste¬ 
riorly sub-truncated, and constituting the sixth of the total length. Pectoral spines serrated upon their inner and outer 
aspects. 
Before we allude any further to the zoological traits characteristic of the present species, we 
have a few words to say respecting the accompanying figures : the snout is less acute than in 
fig. 4 ; the upper jaw ought not to project "beyond the lower one ; the postnasal barbels are once 
again as long as represented on fig. 5 ; the mental (chin) barbels are longer than exhibited in 
fig. 6, since both pairs extend beyond the edge of the gill membrane, which forms the posterior 
outline of said fig. 6 ; and, finally, the mouth hardly shows in a view from beneath, so that 
the same ought not to be seen on the same fig. 6, and, if at all exhibited, it ought to extend to 
the very base of the maxillar barbels, that is, a good deal larger than apparent on that figure. 
The body is deeper than long, being compressed along its entire length, more so, however, 
posteriorly than anteriorly. The head is longer than broad, very much depressed, broader 
than deep even at the occipital region ; it constitutes somewhat less than the fourth of the 
whole length. In a view from above (fig. 5) the snout appears regularly rounded and rather 
narrower than a section across the occiput. The jaws are of equal length, and the mouth, 
although well developed, is but of medium size, when compared to other species, its nearest 
allies. The eyes are rather small, sub-circular in shape ; their horizontal diameter entering 
about six times and a half in the length of the side of the head, and four times on the inter¬ 
ocular space above. The maxillar barbel extends beyond the gill aperture, and somewhat, 
also, beyond the insertion of the pectoral fins. The nasal barbel and those situated under the 
chin have already been alluded to ; they are, comparatively, quite elongated. 
The anterior margin of the dorsal fin is equidistant between the extremity of the snout and 
the adipose ; the spine is missing upon the specimen figured, it having accidentally been broken 
off; the fin itself is quite narrow and high. The caudal, which constitutes the sixth of the 
total length, is posteriorly truncated or sub-concave. As to the anal, it is rather deep and of 
but moderate length, its base entering five times in the total length ; the tip of its posterior 
rays, in being inclined backwards, extend somewhat further back than the posterior edge of the 
adipose. The ventrals are broad and short, being inserted nearer the anterior edge of the anal 
than the base'of the pectorals; their extremities extend to the origin of the anal, and hence 
overlap the vent. The pectorals are of moderate development, the spine at their external 
margin being finely serrated on its outer as well as on its inner aspect. 
D I, 6 ; A 22 ; 0 6, 1, 8, 7, 1, 6 ; Y 8 ; P I, 9. 
Needless to say that the skin is smooth, since it is so in all the species of the genus. The 
lateral line is nearly straight from the supra-scapular region to the base of the caudal, being, 
anteriorly, nearer the dorsal than the ventral outline. 
