eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 153 



to the base of the last ray; inner mental barbels considerably in advance of the 

 outer. 



Distance of dorsal spine from snout 2.4 in the length, the spine about half the 

 length of the head, roughened with antrorse notches in front towards the tip, 

 smooth behind; dorsal rays nearly all of the same height, equal to head less snout; 

 caudal notched, the upper lobe longer, nearly equal to the length of the head; and 

 rounded, reaching caudal; ventrals to anal; pectorals not to ventrals; pectoral 

 spine strong, about equal to head without snout, with retrorse teeth along its 

 entire posterior margin, its anterior margin with antrorse teeth which, in the adult, 

 are nearly as long as the spine is wide. 



Marbled, dark and light brown, without distinct markings on the body, the 

 area between the dorsals and below the posterior part of the adipose lighter in the 

 younger specimens. Margin and a variable median band on the posterior rays 

 of the dorsal light; caudal, anal, ventrals and pectorals profusely spotted, the 

 margins hyaline. 



In the specimens mentioned by Miiller and Troschel and by Peters the premaxil- 

 lary band of teeth have a backward projecting angle. Both are in such a bad state 

 of preservation that I am not sure whether they are to be referred to this species 

 or not. 



29. Pseudopimelodus albomarginatus sp. nov. (Plate XI, fig. 1.) 



Pseudopimelodus albomarginatus Eigenmann, Repts. Princeton Univ. Exp. Pata- 

 gonia, III, 1910, 384 (name only). 



Type, 98 mm. Tukeit. (Carnegie Museum Catalog of Fishes No. 1680.) 

 Cotypes, twenty-one specimens, 33-108 mm. Tukeit. (C. M. Cat. No. 1681 

 a-d; I. U. Cat. No. 12057.) 



Cotype, one specimen, 90 mm. Waratuk. (C. M. Cat. No. 1682.) 

 Head 2.66-2.9; depth 4.66; D. 1,6; A. 10; eye 4 in snout; 12 in head, 5 in 

 space between the eyes. 



Snout much depressed, head flat above; width of head but very little less 

 than its length, its height equal to half its width; anterior nostrils with a tube 

 projecting slightly beyond the upper lip; jaws equal, width of mouth equals length 

 of head without the snout; width of premaxillary bands of teeth about 6 in their 

 anterior margin, a long pointed backward projecting angle; maxillary barbel not 

 quite reaching gill-opening; outer mental barbel scarcely shorter. 



Distance between snout and dorsal spine 2.25-2.3 in the length, the spine 

 slightly rough on the upper half of its margins; dorsal rays of nearly equal height, 



