Durbin : The Expedition to British Guiana. 63 



Cotypes, 6 specimens, 35-58 mm. Tumatumari. (C. M. Cat. No. 

 1462, #; I. U. Cat. No. 11915.) 



Cotypes, 11 specimens, 46-54 mm. Crab Falls. (C. M. Cat. No. 

 1 163, a-c ; I. U. Cat. No. 11916. ) 



Cotypes, several specimens. Rockstone. (C. M. Cat. No. 1464, 

 a-e \ I. U. Cat. No. 119 17.) 



Cotype, 1 specimen, 45 mm. Gluck Island. (C. M. Cat. No. 

 1465, a.) 



Distinguished by large eye, snout almost as long as the eye ; mouth 

 large, maxillary almost straight behind. Slender fishes with all fins 

 hyaline. Humeral spot small, a black line at the base of the anal. 



Head 3.3-3.66, depth 3.66-4.66 ; D. 11, A. 17 to 20 ; scales 5-30 

 to 34-3; eye large, slightly longer than wide, 2.75 in the head; 

 interorbitals almost flat, almost equal to the eye, 3 in the head. 



Compressed, head at the base of occipital process two-thirds to 

 four-fifths the greatest depth. Preventral region rounded, without 

 complete series of median scales. Postventral region narrow. Pre- 

 dorsal region rounded with a complete median series of eight to twelve 

 scales. 



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

 dorsal, bordered by two or three scales. Interorbital nearly flat. 

 Frontal fontanel small, triangular, narrower than the parietal ; two- 

 thirds the length of the parietal without the occipital groove. Second 

 suborbital leaving considerable naked margins behind and below. 

 Maxillary straight, eight-tenths as long as the eye. Mandible a little 

 longer than the eye, 2.5 in the head. Premaxillary with three or four 

 tricuspid teeth in the outer row and six tricuspid teeth in the inner row. 

 Maxillary with three to six tricuspid or occasionally conical teeth. 

 Dentary with a graduated series of four or five teeth also tricuspid. 



Gill rakers 6 + 9. 



Scales cycloid, regularly imbricate, striae few, variable in number ; 

 no interpolated scales nor rows of scales. Caudal scaled for over half 

 way to the end of the lobes. Anal sheath short, consisting of the edge 

 of three large scales. Lateral line with pores developed on seven to 

 twelve scales, very slightly decurved. 



Origin of the dorsal equidistant from the snout and caudal, penul- 

 timate ray one-third the longest, which is four in the length. Origin 

 of the anal on the vertical from the third scale behind the dorsal. 

 Anal very deeply emarginate, the longest ray just reaching the base of 



