28. CHALCINUS. 341 



guished their species by the produced middle caudal rays ; but that 

 character, being dependent on age, and absent in young individuals, 

 cannot prove either the identity or distinctness of two species. Kner'a 

 fish is distinguished by the increased number of anal rays, in which 

 it agrees with no other species, except with Ch. angulatus, Spix. 

 Indeed, it is probable that both are identical, in spite of the differ- 

 ences which become apparent on comparison of the two figures quoted ; 

 for it is evident that the figure given in Spix's work, and taken 

 from an immature example, is incorrect in several respects, repre- 

 senting the lateral line in the upper part of the body, the scales of 

 the thoracic region small, &c. The lateral line of the Chalcines is 

 sometimes indistinct, so that it is difficult to point out its true course. 



2. Chalcinus brachypomus. 



? Chalceus rotundatus, Schomb. Fish. Guian. i. p. 209. 



Chalcinus brachipomus, Cuv. $• Val. xxii. p. 259. 



- — i- trifurcatus, Casteln. Anim. Amer. Sua 1 , Poiss. p. 70. pi. 37. fig. 1. 



miillerii, Be Fil. Rev. et Mag. Zool. 1853, p. 164. 



D. 11. A. 28. V. -7. L. lat. 34. L. transv. 5*. Vert. 18/20. 



The height of the body is contained thrice in the total length 

 (without caudal), the length of the head four times and one-third; 

 operculum twice as high as long, reaching nearly to the vertical from 

 the axil of the pectoral. The scales above the lateral line and in 

 the thoracic region are much larger than the others. The distance of 

 the origin of the dorsal fin from the root of the caudal is contained 

 once and two-thirds in its distance from the extremity of the snout. 

 Pectoral one-third longer than the head. The middle caudal rays 

 are somewhat produced beyond the margin of the fin in mature 

 individuals. Silvery, iridescent : caudal and pectoral fins blackish 

 behind. 



Young specimens have the body somewhat less elevated, and the 

 pectoral extending nearly to the vent. 



Guianas, Brazil. 



a-b. Adult and young. Essequibo. Purchased of Mr. Ehrhardt. 

 c. Adult : skeleton. Essequibo. Purchased of Mr. Ehrhardt. 



3. Chalcinus auritus. 



Cuv. 8f Val. xxii. p. 262 ; Casteln. Anim. Amer. Sud, Poiss. p. 69. pi. 36. 

 fig. 3. 



D. 11. A. 26. V. 7. L. lat. 44. 



The height Oj. the ooiy is two-ninths of the total length (with the 

 caudal), the length of the head one-fifth. The operculum extends 

 backwards to the vertical from the axil. Pectoral reaching to the 

 middle of the ventral (in a specimen 10 inches long). ( Val.) 



Rio Araguay. 



