428 A Revision of the 



Plumbeous above, abruptly silvery below the third series of scales 

 above the lateral line. An oval blackish spot near the fortieth scale of 

 the lateral line, its shorter, vertical diameter about equal to half an 

 orbital diameter. 



Head, 3i-3^; depth, 3M. D. 12-(13 when last ray is divided); A. 

 10-11. Scales, 12-67 to 76-11. 



29. CtJRimATUS ISOGNATHUS sp. nov. 



Types No. 20,314, one specimen, .155 m. to base of caudal. Lago Alexo; 

 S. V. R. Thayer. 

 No. 20,214, one specimen, .135 m. to base of caudal. 19a; W. 



James. 

 No. 20,208, one specimen, .13 m. to base of caudal. Manacapuru; 



W. James. 

 No. 20,225, one specimen, .12 m. to base of caudal. San Paolo; 



W. James. 

 No. 20,224, one specimen, .14 m. to base of caudal. San Paolo; 

 W. James. 

 Related to C. rutiloides and C. asper. The pre ventral region broad, 

 rounded, the jaws equal. 



Shape of rutiloides, the dorsal and ventral outlines equally arched. 

 Postventral region trenchant. Back broad, rounded. 



Profile regularly convex, not depressed at the occiput; mouth termi- 

 nal. Head broad. Eye comparatively small, 1 in snout, 4 in head, 2 in 

 interorbital. 



Scales all ciliate; caudal naked. 



Fins all low, highest dorsal ray shorter than the head. Ventrals not 

 reaching to vent, pectorals not to ventrals. 

 Silvery, bluish above. 



Head 3f-8f; depth 2|-3. D. 12-13; A. 11-12. Scales 12 or 13-51 to 

 53-8 or 9. 



30. CURIOTATIJS KNCIRII. 



Curimatus cyprinoides Kner, '59a, 143 (Barra do Rio Negro; Surinam), 



— not of Linnaeus. 

 Curimatus knerii Steind., '76a, 35 (Teffe); id. '81a, 35 (Teffe; Manaos; 

 Rio Branco; Surinam). 



Habitat, Surinam, Solimoens, Amazon west of Rio Para. 



Many specimens. Montalegre; Porto do Moz; Rio Negro; Tonantins; 

 Lake Hyanuary, 



Dorsal and ventral outline about equally arched; form rather deep 

 and compressed. Preventral region flat, with a median series of en-^ 

 larged scales and lateral keels; postventral region trenchant, with a 

 median series of equitant scales. Back rounded. 



Scales rather small on the back, becoming a little larger toward the 



