170 p. HEMILOPTERUS. 



line is represented as serrated, >vhich we do not per- 

 ceive. The cirrhi on the upper jaw of Spix's fish 

 exceed the pectorals in length; in the other they 

 are shorter by three-quarters of an inch in the re- 

 duced drawing; but witliout the examination of 

 specimens, we could not be sure that these discre- 

 pancies were sufficient for specific distinction. In 

 colouring, our drawing shows deeper tints ; the 

 upper half of the body is olive-brown, shaded into 

 a dark line at the junction of the colour with the 

 pale straw-yellow of the lower parts, which shades 

 into brick-red on approaching the dark lines; the 

 dorsal and adipose fins, with the tail, are brick red, 

 shading into olive at their bases ; the eyes are repre- 

 sented blue. The following formula of the fin rays 

 may be compared together : — 



Schomburyk. D. 1/7— P. 1/8_V. G_A. 10— C. 24— Br. 8. 

 Agassiz. 8 10 7 8* 17t 



Valenciennes. 1/7 1/9 6 8 17:1: 9. 



Mr. Schomburgk remarks : — " A fish attaining 

 from three to four feet in length, and common to all 

 the rivers of Guiana. The head broad and depressed ; 

 the helmet, which is formed by the cranium, is 

 rough or shagrined, and a distinct osseous plate in- 

 tervenes between it and the spine of the first dorsal 

 fin. The lateral line is curved, commencing near 

 the intervening buckler, and terminating towards 

 the middle of the tail. The nose-holes or nostrils 

 are double, — the first pair near the snout, the second 

 mid- way between the snout and the eyes ; the eyes 



* Two small. f 6, 8 minores. J Et quelques petits. 



