334 characinid^:. 



behind the front series. Nostrils close together, separated by a 

 valve only. Gill-openings wide, the gill-membranes being united 

 for a short space in front, but not attached to the isthmus ; gill- 

 rakers slender, lanceolate. 



South America, east of the Andes. 



1. Brycon opalinus. 



Chalceus opalinus, Cuv. Mem. Mus. v. p. 351. pi. 26. fig. 1; Cuv. SrVal. 



xxii. p. 244. 

 ? Characinus amazonicus, Spix, Pise. Bras. tab. 35. 

 ? Chalceus amazonicus, Agass. in Spix, Pise. Bras. p. 68. 



B. 4. D. 11. A. 28. V. 10. L. lat. 45. 

 Coloration uniform, without spots. (C. df V.) 

 Brazils. 



According to the figure, the scales of Chalceus amazonicus are 

 much smaller than those of B. opalinus, so that the identity of both 

 fishes remains doubtful until the typical specimen of the former is 

 reexamined. 



2. Brycon nattereri. 



Chalceus opalinus, Kner, Denkschr. Acad. Wiss. Wien, 1860, xviii. 

 p. 10 (not synon.). 



D. 11. A. 23. L. lat. 50. L. transv. 8/4. 

 A large black spot at the base of the caudal fin. {Kner.) 

 Irisanga. 



3. Brycon bahiensis. 



D. 12. A. 25. V. 8. L. lat. 43. L. transv. ll/5f 



The height of the body is contained thrice and one-third in the 

 total length (without caudal), the length of the head four times. 

 Intermaxillary teeth in three series ; the lateral portion of the inner 

 series of the mandible extends forwards to the front teeth. The 

 origin of the dorsal fin is behind the root of the ventral, and some- 

 what nearer to the base of the caudal than to the extremity of the 

 snout. The pectoral does not extend to the ventral. Belly tren- 

 chant behind the ventral, rounded in front. The lateral line becomes 

 distinct below the dorsal, being scarcely visible on the anterior part 

 of the body. Greenish, shining silvery ; humeral and caudal spots 

 present, but indistinct. 



Bahia. 



a. Six inches long. From Dr. 0. Wucherer's Collection. 



4. Brycon falcatus. 



Mull. 8f Trosch. Hor. Ichth. i. p. 29. tab. 6. fig. 1. 



B. 4. D. 11. A. 27-29. V. 8. L. lat. 47-49. L. transv. 10/6. 

 Vert. 21/20. 



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



