Along the Esseouebo and Potaro. 161 



upper surface of the head and neck, and of a prevailing 

 greenish-purple or black colour, fading into a silvery 

 grey below, with obscure dark spots. The head is broad 

 and flattened, widening slightly to the pectorals, and 

 nearly one-fourth the length of the body (including the 

 caudal fin); the upper jaw longer than the lower; teeth 

 small, fine, and crowded in a broad band upon both 

 jaws. The band upon the palate is separated by a narrow 

 interval; the eyes are small, and with bluish-grey iris. 

 The barbels are six in number: the first mandibulary 

 pair short; the second longer, reaching to the insertion 

 of the pectoral fins ; and the upper pair very elongated, 

 reaching nearly to the end of the ventral or pelvic fins. 

 The adipose fin is high in front, sloping down to the 

 body behind, and slightly longer than the anal. 

 D. 1/6. P. 1/9. V. 1/5. A. 13 (12). 



The first dorsal ray is a thick spine, smooth in front, 

 jagged and finely spinose posteriorly, and produced above 

 into a distinct whip-like filament. The first pectoral ray 

 is a sharp, strong spine, serrated on the hinder mar- 

 gin. The first ventral is enlarged, but flexible. The 

 tail is symmetrically lobed, but the first ray of the upper 

 lobe is produced into a whip-like filament. The first 

 anal ray is very small and short and almost inconspicuous. 

 The lateral line is distinct, and much curved, continuous 

 behind with a prominent- rib. 



The body, behind the pectoral fins, rises high upwards 

 to the dorsal fin, where a transverse section is nearly 

 triangular in shape, though the sides bulge out and are 

 rounded: it becomes slightly flattened above to theadipose 

 fin, where it rises a little and sinks again to the tail. 

 Behind the pelvic fins the body becomes sub-cylindrical. 



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