206 PROCEEDINGS OF THE NATIONAL MUSEUM tol. 94 



base of supraoccipital process; belly usually silvery, but occasionally 

 a few diffuse spots occur anteriorly; peritoneum pale. 



Named coprophagus in reference to its feeding habits. 



Remarks. — This new subspecies is so distinct from P. clarias clarias 

 of the Magdalena River system that it might have been best to give it 

 the rank of a full species. The relationships of P. clarias clarias and 

 other populations close to clarias ranging southward from the Mara- 

 caibo Basin need careful study, for they appear to differ somewhat 

 from the Magdalena form, that in the Maracaibo Basin, and also 

 P. clarias punctatus from Panama. P. clarias clarias has a plain color- 

 ation without spots or streaks, P. clarias punctatvs is spotted when 

 young but plain in color when older, while P. clarias coprophagus is 

 profusely spotted with pale streaks at all sizes and ages. This new 

 subspecies differs from all other species with a similar color pattern 

 in its very short and high adipose fin, the height usually continued 

 about 2.5 times in its total length. In the key other differences are 

 given that aid in its separation from species reported in Colombia or 

 Venezuela. 



In Lago Maracaibo P. clarias coprophagus is one of the commonest 

 species and is taken some distance up the rivers. Around the docks 

 in the oilfields and along the waterfront at Maracaibo it is a scavenger, 

 eating any refuse that it can get. Off Lagunillas in Lago Maracaibo 

 I saw it swimming in large schools at the sui-face just under the film 

 of oil that covers the water in that part of the lake. Often it sweeps 

 its long blackish maxillary barbels forward and backward under this 

 oil film, and on a few occasions I have seen individuals swallow large 

 globules of thick petroleum more or less settling in the water. Because 

 of its feeding habits around the oilfields it is thorouglily despised. 



PIMELODUS CLARIAS CLARIAS (Bloch) 



Silvrus clarias Block, Naturgescliichtc der auslandischen Fisclio. pi. 35, figs. 1-2, 

 1785 [=S. clarias Linnaeus in part; not S. clarias Hasselquist, which is 

 Synodontis clarias from the Nile (ref. copied)]. 



Pimelodus clarias (Bloch) Steindacrner, Denkschr. Akad. Wiss. Wien, vol. 39, 

 p. 15, 1878 (Magdalena River) (I have selected this locality as representing 

 the type locality on which to base comparison); vol. 41, p. 158, 1879 

 (Ciudad Bolivar; Rio Mamoni at Chepo). 



Pimelodus maculatus Peters, Monatsb. Akad. Wiss. Berlin, 1877, p. 470 (Cala- 

 bozo, Venezuela). — Pelleorin, Bull. Mus. Hist. Nat. Paris, vol. 5, p. 158, 

 1899 (Apure River, Venezuela). 



IPseudariodes pantherinus Lvtkes, Vid. Mcdd. Naturh. Foren. Kj0benhavn, pts. 

 12-16, p. 192, 1874 (Caracas, Venezuela). (One of Liitken's specimens, 

 probably a cotype, is in the United States National Museum, No. 44970, 

 and it greatly resembles my specimens of Pimelodus clarias coprophagus from 

 the Maracaibo Basin except in certain color characteristics. Liitken's types 

 of pantherinus need careful comparison with the Maracaibo form. Perhaps 

 they were not taken at Caracas.) 



