eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 283 



Origin of dorsal over origin of ventrals; pectorals reaching half-way to middle 

 of ventrals ; ventrals to anal ; origin of anal on a vertical from middle of last dorsal 

 ray. No adipose fin. 



Back uniform gray, median darker line wanting; a light band from end of 

 snout to upper part of middle, of caudal; a black band from end of mandible to 

 lower part of middle of caudal; darkest above pectorals and above middle of 

 ventrals; a few chromatophores along base and in front of the anal fin; fins mostly 

 hyaline, their chromatophores few. 



139. Nannostomus simplex Eigenmann. (Plate XXXVI, fig. 6.) 

 ? Nannostomus anomalum Steindachner, " Ichthyologische Beitrage," v, 1876, 81 



(Rio Negro; Amazon at Obidos). 

 Nannostomus simplex Eigenmann, Ann. Carnegie Mus., VI, 1909, 42; Repts. 



Princeton Univ. Exp. Patagonia, III, 1910, 427. 



Type, 25 mm. Lama Stop-Off. (Carnegie Museum Catalog of Fishes No. 

 1167.) 



Cotype, 29 mm. Lama Stop-Off . (I. U. Cat. No. 11692.) 



Closely allied to N. auratus and N. minimus. 



Head 3.5; depth 4.5; D. 10; A. 10; five scales between dorsal and ventral, nine 

 before dorsal, twenty-four in a lateral series. Eye a little greater than snout, 3 in 

 the head, equal to the interorbital. 



Pectorals reaching half-way to second third of the ventrals, ventrals half-way 

 to tip of last anal ray; origin of anal under tip of last dorsal ray. No adipose fin. 



Back dark gray with a median dark line; a light band from snout to base of 

 upper rays of middle of caudal; a black band through mandibles and snout to 

 base of lower caudal, and continued on the two middle rays; ventral surface plain, 

 except for a spot between the tips of the ventrals; chromatophores of the lateral 

 band scattered above the pectorals and above the front part of the anal. 



Pcecilobrycon Eigenmann. 

 Po3cilobrycon Eigenmann, Ann. Carnegie Mus., VI, 1909, 43. 



Type, Pttcilobrycon harrisoni Eigenmann. 



Skull truncate, without a crest; no fontanel; no lateral line; pectorals normal; 

 teeth broad-tipped, five-pointed. 



Key to the Guiana Species of Pcecilobrycon. 

 a. A single dark band from chin to near end of middle caudal ray, alight band above it; back chocolate. 



harrisoni. 

 aa. A median dorsal and three lateral dark bands trifasciatus. 



