200 MEMOIRS OF THE CARNEGIE MUSEUM 



fontanel surrounded by bone; maxillary barbel reaching to or beyond tip of the 

 humeral process, mental barbel 2.5-3 times as long as the eye. 



Dorsal spine equal to head without the snout or a little longer but not equal 

 to the length of the head, rough in front, with recurved hooks for over half its 

 length from the tip on the posterior margin; pectoral spine as long as the head, 

 with antrorse teeth in front and larger retrorse teeth behind; caudal obliquely 

 rounded. 



Color variable, much lighter in those inhabiting muddy water, with a light 

 band across the head behind the eye, the dorsal plate also light, sides strigate; 

 much darker to black in those inhabiting clear waters, the sides strigate. 



The specimens from Chipoo Creek, a tributary of the Ireng, differ from those 

 near the coast in having the maxillary barbels a little shorter, reaching to or not 

 quite to the tip of the humeral process, the mental barbels 1.5-1.75 times as long 

 as the eye. 



70. Trachycorystes obscurus (Giinther). (Plate XVII, fig. 2.) 



Auchenipterus obscurus Gunther, Ann. and Mag. Nat. Hist., (3), XII, 1863, 442 



(Essequibo); Catalogue, V, 1864, 195. 

 Trachycorystes obscurus Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), 



I, 1888, 154; Occasional Papers Cal. Acad. Sci., I, 1890, 275. — Eigenmann, 



Repts. Princeton Univ. Exp. Patagonia, III, 1910, 396. 



I have examined the types in the British Museum and two specimens in the 

 Berlin Museum, all collected by Ehrhardt. 



No specimens of this species were secured by me. 



The species is readily distinguished by its emarginate caudal. 



D. 1,5; A. 19-20; maxillary and post-mental barbel extending to, or somewhat 

 beyond, the tip of the humeral process; mental barbel 2 or 3 times as long as the 

 eye; dorsal serrate along its anterior edge; pectoral serrate along both edges; dorsal 

 spine shorter than the pectoral spine, which equals the head in length; caudal 

 emarginate, the upper lobe scarcely longer than the lower. Uniform brownish black. 



Pseudauchenipterus Bleeker. 



Felichthys Swainson, Class. Fishes, Amph., and Rept., II, 1839, 305 (sp). — Swain, 



Proc. Acad. Nat. Sci. Phila., 1882, 281 (nodosus). 

 Pseudauchenipterus Bleeker, Nederl. Tijdschr. Dierk., I, 1863, 88 (nodosus). 



Type, Silurus nodosus Bloch. 



