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.) 



Cotypes, 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. 

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



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

 1062«-e; I. U. Cat. No. 11750.) 



Head 3.8-4; depth about 2.66; D. 11; A. 33-37, usually 35 or 36 ; 55 scales 6-33 

 to 36 5C -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; preventral area flat, 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 bluntly keeled, with about ten median 

 scales. 



Occipital process one-fourth or one-fifth of the distance from its base 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; prcmaxillary- 

 niaxillary 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-lobed and one to three conical teeth; maxillary 

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

 maxillary. 



Gill-rakers 4 + 9. 



Scales everywhere regularly imbricate, without interpolate scales, each scale 

 with several radiating strise; 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. 



55 Of those examined three with 33, four with 34, .six with 35, seven with 30 and two with 37. 



56 Of those examined two with 33, three with 34, eight with 35, ten with 36. 



