EIGENMANN: the freshwater fishes of BRITISH GUIANA 367 



Cotypes, five specimens, 46-64 mm. Sand-bank at Tukeit. (C. M. Cat. 

 No. 1059; I. U. Cat. No. 11747.) 



Coty])es, four specimens, 68-85 mm. Amatuk. (C\ M. Cat. No. 1060; I. U. 

 Cat. No. 11748.) 



Cotypes, sixteen specimens, 41-64 mm. Crab Falls. (C. M. Cat. No. 

 1061n-e; I. U. Cat. No. 11749.) 



Cotypes, eighteen specimens, 36-64 mm. Rockstone. (C. M. Cat. No. 

 1062o-e; I. U. Cat. No. 11750.) 



Head 3.8-4; depth about 2.66; D. 11; A. 33-37, usually 35 or 36 ;« scales 6-33 

 to 3656_4 to 5; eye 2.33-2.66; interorbital 3.5-4. 



Elongate rhomboidal, heavy forward, the tail much compressed; profile com- 

 pressed over the eye, arched in front of the dorsal; prevcntral area fiat, with two 

 series of large scales overlapping along the middle, a small scale in the angle of each 

 pair of the overlapping scales, except the two pairs between the pectorals; midline 

 of postventral area naked; predorsal area bkmtly keeled, with about ten median 

 scales. 



Occipital process one-fourth or one-fifth of the distance from its ba.se to the 

 dorsal, bordered by four scales on the sides; interorbital flat, the upper margin of 

 the eye on a level with the middle of interorbital; frontal fontanel as long as the 

 parietal, narrower than the latter, reaching to above the anterior margin of the 

 pupil; second suborbital corrugate, leaving a wide naked margin; premaxillary- 

 maxillary border without a distinct angle, moderately oblique; a maxillary of 

 nearly equal width throughout, not slipping under or over the first suborbital; 

 snout blunt, the lower jaw included. 



Mandible with four to six narrow graduated teeth, with a large central and a 

 minute lateral cusp on each side; sides of mandible with about ten minute teeth; 

 premaxillary with four to seven teeth in a line parallel with the second row, which 

 consists of about five to seven three-lobcd and one to three conical teeth ; maxillary 

 with eleven to sixteen conical or three-lobed teeth along about half the length of the 

 maxillaiy. 



Gill-rakers 4 + 9. 



Scales everywhere regularly imbricate, without interpolate scales, each scale 

 witli several radiating stria^; lateral line slightly decurved; anal sheath of a single 

 series of graduate scales along the base of the first rays; caudal naked; axillary 

 scale small. 



** Of those examined three with 33, four with 34, six. with 35, .seven with 36 antl (wo with 37. 

 *" Of tho.se examined two with 33, three with 34, eight udtli 35, ten with 36. 



