25. CHALCIN0PSI3. 337 



scales of moderate size ; lateral line complete. Belly compressed in. 

 front of the ventrals, trenchant behind them. Cleft of the mouth 

 rather wide. Intermaxillary with three or four rather irregular 

 series of teeth, which are notched or tricuspid ; edge of the maxillary 

 with small teeth ; mandible with a series of strong tricuspid teeth, 

 and with a pair of conical teeth in the middle behind the front 

 series. Nostrils close together, separated by a valve only. Gill- 

 openings wide, the gill-membranes being not attached to the isthmus, 

 separate ; gill-rakers Slender, lanceolate. 

 Central America ; Ecuador. 



* Intermaxillary teeth in four series. 



1. Chalcinopsis dentex. 

 Brycon dentex, Giinth. Proc. Zool. Soc. 1860, p. 240. 

 D. 11. A. 35-36. L. lat. 48-55. L. transv. 9 j^. Vert. 23/22. 



The height of the body is contained thrice and one-fourth or thrice 

 and one-third in the total length (without caudal), the length of the 

 head four times and one-third or four times and two-thirds. The 

 maxillary does not quite extend to below the centre of the eye. Snout 

 as long as the eye in young examples, but much longer in adult ones. 

 Interorbital space convex, its width being much more than the dia- 

 meter of the eye in old specimens. The origin of the dorsal fin is 

 nearer to the root of the caudal than to the extremity of the. snout ; 

 its hinder rays are vertically above the anterior anal rays. The free 

 portion of the tail is considerably longer than high. Caudal deeply 

 forked. The pectoral extends to, or nearly to, or a little beyond, 

 the ventral. Silvery, sometimes with a reddish hue ; some of the 

 scales have occasionally a black margin, or are spotted with black ; 

 humeral part of the gill-opening black ; sometimes a black spot at 

 the root of the caudal. Anal fin generally with a black margin. 



Guatemala, Ecuador. 



a-d. Adult, half-grown, and young. Esmeraidas. From Mr. Fraser's 



Collection. — Types of the species. 

 e-g. Adult : 16 inches long. Rio Motagua. From the Collection of 



Messrs. Godman and Salvin. 

 h. Adult. Rio Usumacinta. From the Collection of Messrs. Godman 



and Salvin. 

 i. Young. Yzabal. From the Collection of Messrs. Godman and 



Salvin. 

 k. Adult male : skeleton. Rio Motagua. From the Collection of 



Messrs. Godman and Salvin. 



2. Chalcinopsis striatulus. 



Xner, Sitzgsber. Acad. Wiss. Munch. 1863, p. 226. 



D. 10-11. A. 36. L. lat. 73-74. L. transv. 13/8. 



The length of the head is one-fifth of the total length (with the 

 vol. v. z 



