Eioenmann : The Expedition to British Guiana. 27 



It is difficult to determine with certainty whether the two minute 

 specimens from Savannah Landing belong to this species. 



Deuterodon potaroensis sp. now 



Type, 43 mm. (No. 1053 Carnegie Museum Catalog of Fishes.) 

 Amatuk Cataract, Potaro River. 



Cotypes, 5 specimens, 39-50 mm. Amatuk Cataract, Potaro River. 

 (C. M. Cat. No. 1054; I. U. Cat. No. n 744.) 



Cotypes, 3 specimens, 31-35 mm. Waratuk Cataract, Potaro River. 

 (C. M. Cat. No. 1055 ; I. U. Cat. No. 11745.) 



This species was taken by poison in a little side branch of the War- 

 atuk Cataract and in the same way in a larger branch of the Amatuk 

 Cataract. 



Head 3.8-4; depth 3.2-3.5 ; D. 9 or 10 ; A. 24 or 25 (rarely 27) ; 

 scales 6-37 to 40-4. Eye 2.5 ; interorbital equals eye. 



Elongate, little compressed, heavy at shoulder ; dorsal and ventral 

 profiles equally arched, without hump or depressions ; preventral area 

 narrowly rounded, with a median series of scales ; postventral area 

 compressed to a narrow edge ; predorsal area keeled, with a median 

 series of about thirteen scales. 



Occipital process about one-fifth of the distance from its base to the 

 dorsal, bordered by three scales ; head narrow, smooth above, slightly 

 convex ; frontal fontanel much shorter than the parietal, narrow ; 

 second suborbital leaving a naked area about one-third as wide as its 

 own greatest width ; maxillary longer than snout, but not quite equal 

 to eye; premaxillary with three three-pointed teeth in the front row 

 and five three- to five-pointed ones in the second. Denticles of the 

 second row in a more or less open crescent ; four or five maxillary 

 teeth similar to those of the inner row of the premaxillary. Mandible 

 with seven graduated multicuspid incisors, followed by one or two 

 conical incisors. 



Gillrakers 6 + 12. 



Scales regularly imbricate, without interpolated or omitted rows ; 

 each scale with numerous nearly parallel striae ; anal sheath of a few 

 scales in a single row along the base of the anterior rays. Caudal 

 naked; lateral line but little decurved ; a well-developed axillary scale. 



Origin of dorsal a little nearer snout than caudal, its penultimate ray 

 a little more than half as long as the longest ray which is about one- 

 fourth of the length. Margin of anal straight, the rays graduate from 



