288 MEMOJRS OF THE CARNEGIE MUSEUM 



Characidium Reinhardt. 



Cliaracidium Reixhardt, Overs. Dan. Vidensk. Selsk. f'orh., 1866, 56, pi. 2, figs. 



1 and 2. 

 Chorimyderus Cope, Am. Nat., XXVIII, 1894, 67 (tenuis). 

 Nannocharax Boulenger, BoU. Mus. Zool. ed. Anat. Comp. Torino, X, 1895, 2 



(borellii) . 

 Poecilosomatops Fowler, Proc. Acad. Nat. Sci. Phila., 1906, 323, fig. 17 (etheostoma) . 



Type, Characidium fasciatum Reinhardt. 



Premaxillary and dentary each with a single series of conical or three-pointed 

 teeth; no frontal fontanel, a small circular occipital fontanel; a triangular occipital 

 process; adipose fin present; lateral line complete. Small or minute fishes of the 

 sand-bars and cataracts, living among the rocks or burrowing in the sand, much as 

 do the Etheostomatine fishes of North America. 



Key to the Guiana Species of Characidium. 

 a. Tips of outer pectoral rays thickened; color well-developed. (Inhabitants of rocky places and creeks.) 



6. A broad lateral band, not crossed by dark bars laterale. 



66. Lateral band crossed by vertical bars. 



c. Pectorals not reacliing ventrals; about four lateral bands or streaks, crossed by about eight 



bars vintoni. 



cc. Nearly uniform blue-black; dorsal, caudal and ventrals conspicuously barred with wliite and 



black blennioides. 



ccc. Straw-color, with a narrow black band from tip of snout to base of middle caudal rays, and about 



ten brown cross-bands fasciatxim. 



aa. Tips of outer pectoral rays not thickened; pellucid. (On sand-bars, burrowing.) 



(/. Middle of sides with twenty-seven to thirty chromatophores, one or more out of line; back with about 



sixteen cross-bars pelluciduin. 



dd. Sides with numerous crescents of brown; back with aljout thirteen cross-bars pteroides. 



ddd. About ten dark brown cross-bars, most intense on back and along the lateral line, the centers of 

 the scales in the bars colorless catenatum. 



145. Characidium laterale Eigenmann. (Plate XXXVII, figs. 6, 7.) 



Characidium laterale Eigenmann, Ann. Carnegie Mus., VI, 1909, 36; Repts. 



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



Type, 37 mm. Amatuk. (Carnegie Museum Catalog of Fishes No. 1141.) 



Cotypes, three specimens, 29-35 mm. Amatuk. (I. U. Cat. No. 11673.) 



A Zygonectes-like Characidium. 



Head 3.75-4; depth 0; D. 11 or 12; A. 8; scales 4-36-2. 



Eye equal to snout, 3.75 in head. Teeth three-pointed. Pectoral reaching 

 ventrals, its outer rays thickened; ventrals three-fourths to anal; fourth anal ray 



