45. SERRASALMO. 371 



11. Serrasalmo gymnogenys. 



PSerrasalmus humeralis, Casteln. Anim. Amer. Sud, Poiss. pi. 37. fig. 2 * 

 D. 16. A. 33-36. V. 7. L. lat. 95. 



The height of the body is contained once and two- thirds in the 

 total length (without caudal), the length of the head thrice and one- 

 half ; the abdominal profile is very convex, the upper profile of the 

 head, above the eyes, concave. Snout obtuse, the length of the 

 upper jaw, before the eye, being equal to that of the orbit. The 

 second infraorbital is longer than high, and separated from the prae- 

 opercular limb by a broadish strip of naked skin, which is half as 

 wide as the infraorbital itself. The origin of the dorsal fin is mid- 

 way between the extremity of the snout and the posterior end of the 

 lateral line. Pectoral extending to the root of the ventral. Abdo- 

 minal serrature composed of thirty or thirty-one spinous plates. 

 Gill-rakers short, lanceolate. Body with small blackish spots ; an 

 indistinct blackish blotch behind the gill-opening ; caudal fin dark 

 on its base, with a light posterior margin. 



Brazil, Guiana. 



a-b. Adult (8 inches long) and young. River Capin. Purchased 



of Mr. Stevens. 

 c. Adult. British Guiana. Presented by Sir R. Schomburgk. 



12. Serrasalmo maculatus. 



Kner, Denkschr. Acad. Wiss. Wien, I860, xviii. p. 41. taf. 4. fig. 10. 

 D. 15-16. A. 32-36. V. 6-7. 



The height of the body is contained once and four-fifths in the 

 total length (without caudal), the length of the head thrice and one- 

 fourth ; snout obtuse, longer than the eye. The second infraorbital 

 bone is separated from the prseopercular limb by a narrow strip of 

 skin. Abdominal serrature composed of from twenty-nine to thirty- 

 three spinous plates. Body with rounded blackish spots ; an indis- 

 tinct blackish blotch behind the gill-opening ; caudal and anal fins 

 with the margin black, without white edge. {Kner.) 



Bio Guapore. 



13. Serrasalmo elongatus. 



Kner, Denkschr. Acad. Wiss. Wien, 1860, xviii. p. 44. taf. 5. fig. 12. 



D. 15. A. 32-33. V. 7. 



The height of the body is contained twice and two-thirds in the 

 total length (without caudal), the length of the head thrice and one- 

 fifth ; snout pointed. The second infraorbital bone is longer than 



* It is not improbable that Castelnau has figured a speciet iiffierent from the 

 S. humeralis of Valenciennes ; the latter describes the caudal fin as broadly 

 edged with black, whilst in the figure given by Castelnau this fin has a light 

 margin, as in S. gymnogenys. At all events it is almost certain that the two 

 fishes figured by Kner and Castelnau under the name of *S'. humeralis, belong to 

 two distinct species. 



2b2. 



