NATURAL SCIENCES OF PHILADELPHIA. 95 



may appear on re-examination of the latter, the dentition and other charac- 

 teristics not yet being known. 



SCIADES MARMORATUS Gill. 



B. 9. P. I. 10. V. I, 5. D. I, 10. A. 11. 



The head is little longer than broad. The diameter of the eye is contained 

 nine or ten times in the head's length. The vomerine teeth are in two oval 

 patches, nearly as large as the eye, and separated by a moderately narrow 

 interval ; the palatine patches are transversely oval, and smaller than the 

 pupil of the eye. The maxillary barbels extend beyond the base of the cau- 

 dal ; the external mandibular beyond the tips of the pectorals, and the inter- 

 nal beyond the bases of those fins. The dorsal fin is three fourths as high as 

 the head is long. The adipose fin is half as long again as the dorsal. 



The ground color is greyish, and forms meandering lines between the large 

 blackish spots by which it is covered. All the fins are similarly colored, hut 

 the spots at the base of the dorsal are fused into a band. The barbels are in- 

 distinctly anuulated. 



Closely allied to S. longibarbis (Arius? longibarbis Casllenau), but appears 

 to be distinguished by the longer adipose fin and the number of rays ; it may, 

 however, prove to be only a form of that species. Oastelnau has doubtless 

 overlooked the two small areas of teeth on the palate. 



Subfamily CETOPSIN^E. 



Cbtopsis ventralis Gill. 

 P. 10. V. 6. D. 1, 6. A. 29. 



The greatest height enters 4.} times in the length exclusive of the caudal, 

 and 5$ times inclusive thereof! The head enters 4 ; } times in the length 

 exclusive of the caudal fin, and 5| inclusive of it; its breadth does not ex- 

 ceed half its length. The gape is continued under the entire eye. The teeth 

 are in a villiform band on the lower as well as upper jaw, and on the vomer. 

 The ventrals are inserted entirely behind the vertical of the dorsal, and arc 

 connected together by a membrane which is, however, closely connected with 

 the abdomen along the middle, and is not free even at the margin ; the extre- 

 mities of the fins extend to or beyond the anus. The barbels are nearly equal 

 and about two or three times as long as the diameter of the eye. 



The color is greyish, darker above; the basal half of the dorsal is punctu- 

 lated with black. 



This species is most closely related to Cetopsis gobioides Kner, but is distin- 

 guished hy the more compressed head, posterior ventrals, and longer anal.* 



Subfamily TRACHELYOPTERIN^. 



Centromochlus Steindachneri Gill. 



P. I, 7, D. I. 5. A. 7. 



The greatest height equals two thirds of the length of the head, which itself 

 enters about 3| times in the total length, exclusive of the caudal. The eyes 

 are moderately large, the diameter equalling a quarter of the heads length. 

 The maxillary barbels are nearly coterminal with the elongated pectora, fins 

 The dorsal buckler behind is cordate, and its branches expand inwards and 

 extend as far back as the third soft ray. The height of the dorsal is not much 

 less than the head's length ; its spine is obsoletely serrated behind The pei - 

 torals equal nearly a third of the length, and do not reach the ventrals. 1 he 



* The number of anal rays is not given by Kner, but the figure represents twenty-two. 

 1870.] 



