162 MEMOIRS OF THE CARNEGIE MUSEUM 



38. Chasmocranus brevior sp. nov. (Plate XV, fig. 1.) 



Chasmocepl talus brevior Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 

 1910, 384 (name only). 



Type, 56 mm. Waratuk. (Carnegie Museum Catalog of Fishes No. 1662a.) 

 Cotypes, two specimens, 69 mm. Waratuk. (I. U. Cat. No. 12047.) 

 ? One specimen, 23 mm. Amatuk. (C. M. Cat. No. 1663o.) 

 This species differs from longior in having more pointed caudal lobes, and 



especially in the length of the adipose fin, which is contained six times in the length. 



Rhamdia Bleeker. 



Pimelodus Lacepede, Hist. Nat. Poiss., V, 1803, — (sp.). — Cuvier, Regne Animal, 



II, 1817, 203 (sp.).— GtJNTHER, Catalogue, V, 1864, 114 (sp.). 

 Pteronotus Swainson, Class. Fishes, Amph., and Rept., II, 1839, 309 {5-tentaculatus) , 



preoccupied in mollusks. 

 Rhamdia Bleeker, Icth. Arch. Ind. Prodr., I, 1858, 197, 207 (sp.); Nederl. 



Tijdschr. Dierk., I, 1863, 101 (queleni). 

 Pimelonotus Gill, Ann. Lye. Nat. Hist. N. Y., VI, 1858, 391 (vilsoni). 

 Notoglanis GIjnther, Catalogue, V, 1864, 136 (multiradiatus) . 



Type, Pimelodus quelen Quoy and Gaimard. 



Eye with a free orbital margin. Teeth on vomer none or minute; occipital 

 process short, not reaching the dorsal plate; no parietal fontanel; head covered 

 with skin, not granular; caudal forked; barbels terete. 



Key to the Guiana Species op Rhamdia. 

 a. D. 1,6 or 7. 



6. Premaxillary band of teeth rounded laterally. 



c. Maxillary barbel not or very rarely extending to middle of adipose. Space between the eyes 



2.2-2.6 in the head, both caudal lobes rounded, not quite as long as head, the sixth ray 



of the upper lobe from the median cleft longest; eye 3 in the snout, 6.5-7 in the head, 



3 in the space between the eyes; adipose dorsal 2.5 in the length quelen. 



cc. Maxillary barbel extending past middle of adipose; upper caudal lobe pointed; the fifth ray 



of the upper lobe from the median cleft longest; space between the eyes about 2.33 in 



the head sebas. 



bb. Premaxillary band of teeth with a backward projecting angle laterally. Maxillary barbel not 



extending to middle of adipose; space between the eyes 3 in the head; caudal cleft, both 



lobes rounded, the third or fourth ray from the cleft in the upper lobe longest; adipose dorsal 



2-2.4 in the length holomelas. 



aa. D. 1,10; A. 6; maxillary barbel to tip of ventrals arekaima. 



