30 Dr. A. GUnther on some Fishes from the Amazons. 



VII. — Remarks on some Fishes from the River Amazons in the 

 British Museum. By Dr. Albert Gunther. 



A COLLECTION of fishes made by Mr. Bartlett^ juni*., on the 

 Upper Amazons, and acquired for the British Museum, con- 

 tained, besides numerous examples of described species, a few 

 which appear to be new to science*. It aflForded me also the 

 opportunity of comparing the true Prochilodus nigricans of 

 Agassiz with its congener from the Essequibo River (cfr. Fish. 

 V. p. 295). They prove to be specifically distinct, the species 

 from the Amazons having somewhat smaller scales, viz. L. lat. 48. 

 L. transv. 10/9. The height of the body is one-third of the 

 total length (without caudal). The name nigricans must be 

 retained for the Amazons species, whilst the Essequibo fish is 

 most probably identical with P. rubrotceniutus (Schomb.). 



Tetragonopterus Bartlettii, n. sp» 

 D. 11. A. 31. L. lat. 39. L. transv. 8/7. 



The height of the body is contained twice and three-fourths 

 in the total length (without caudal), the length of the head 

 thrice and two-thirds. Interorbital space convex, its width 

 being scarcely more than the diameter of the eye, M'hich is one- 

 third of the length of the head. The upper profile of the head 

 is very slightly concave. The maxillary extends a little behind 

 the vertical from the front margin of the orbit. The origin of 

 the dorsal fin is immediately behind the base of the ventrals. 

 Pectoral extending beyond the base of the ventrals, nearly to the 

 vertical from the origin of the dorsal. Humeral and caudal 

 spots distinct ; body without silvery band. One of the speci- 

 mens has a broad oblique dark band across the middle of the 

 dorsal fin. 



Two specimens, 4 inches long, were in the collection. 



Cynodon pectoralis, n sp. 



This species is closely allied to C. scombroides, but has a 

 greater number of rays in the anal fin, and a much longer and 

 larger pectoral fin. 



D. 13. A. 48. P. 19. V. 10. 



The height of the body is two-sevenths of the total length 

 (with the caudal), the length of the head nearly one-fifth. 

 Scales very small, those of the lateral line about twice the size 



* I observe, in a letter of Prof. Agassiz, addressed to and published by 

 M. Milne-Edwards, that a new genus of freshwater Beloniace from the 

 Amazons is mentioned. I suppose this to be the same fish which was dis- 

 covered by Mr. Bates some fifteen years ago, and is described in the ' Catal. 

 Fish.' vi. p. 256, as Potamorrhaphis (Belone) tceniata. 



