328 CHAEACINID^. 



vex ; its width is more than the diameter of the eye, which is two- 

 fifths of the length of the head. The upper profile of the head is 

 straight ; the maxillary extends to below the front margin of the 

 eye. The origin of the dorsal fin is vertically behind the root of the 

 ventrals. The pectoral extends somewhat beyond the base of the 

 ventral. Humeral and caudal spots present. 



British Guiana. 

 a. Four inches long. Presented by Sir R. Schomburgk. 



** The origins of the dorsal and ventral fius are nearly in the 

 same vertical. 



25. Tetragonopterus chrysargyreus. 



D. 11. A. 28. V. 8. L. lat. 34. L. transv. 7/7. 



The height of the body is a little less than one-half of the total 

 length (without caudal), the length of the head one-fourth ; inter- 

 orbital space convex, its width being scarcely more than the diameter 

 of the eye, which is two-fifths of the length of the head. The upper 

 profile is concave above the parietal region. The maxillary termi- 

 nates below the front margin of the eye. The origin of the dorsal fin 

 is vertically above the middle of the base of the ventral. Caudal fin 

 scaly. The pectoral reaches beyond the root of the ventrals. Silvery, 

 with golden reflexions ; back steel-blue ; a round blackish spot behind 

 the shoulder, above the lateral line. 



Essequibo. 

 a. Fine specimen, 4 inches long. From Mr. Ehrhardt's Collection. 



26. Tetragonopterus grandisquamis. 



Midi. Sf Trosch. Hor. Ichth. i. p. 27. taf. 8. fig. 2. 

 D. 11. A. 28. V. 9. L. lat. 30-33. L. transv. 5/5. 



The height of the body is contained twice and one-sixth in the total 

 length (without caudal), the length of the head thrice and two-thirds ; 

 interorbital space convex, its ^vidth being rather more than the dia- 

 meter of the eye, which is two-fifths of the leng-th of the head. The 

 upper profile is scarcely concave above the eye. The maxillary ex- 

 tends nearly as far backwards as the first infraorbital bone, somewhat 

 beyond the front margin of the eye. The origins of the dorsal and 

 ventral fins are in the same vertical. The pectoral reaches to the 

 base of the ventral fin. Caudal fin scaly. A silvery band along the 

 body, above the lateral line. 



Guianas. 

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



27. Tetragonopterus lepidurus. 



Kner, De/ikschr. Acad. Wins. Wien, 1859, xvii. p. 176. taf. 8. fig. 20. 

 D. 10-11. A. 24-25. L. lat. 36. L. transv. ^. 

 The height of the body is somewhat less than one-third of the 



