330 CHARACINID^. 



larger, its length being contained four times and one-fifth in the 

 total (without caudal) ; the height of the body is contained thrice 

 and one-fourth in its length. Interorbital space flat, its width being 

 equal to the diameter of the eye, which is two-fifths of the length of 

 the head. Upper profile straight above the occiput. Maxillary long 

 and narrow, extending to below the middle of the eye. The origin 

 of the dorsal is vertically somewhat behind that of the ventral ; the 

 pectoral extends to the base of the ventral. Uniform silvery ; caudal 

 fin black, with a pair of large red spots on its basal half. 



British Guiana, 

 a. Three and a half inches long. Presented by Sir R. Schomburgk. 



31. Tetragonopterus caudomaciilatus. 

 D. 11. A. 2G. L. lat. 42. L. transv. 6^/4. 



Similar to T. melanurus. 



The height of the body is two-sevenths of the total length (without 

 caudal), the length of the head two-ninths. The interorbital space 

 is flat, equal in width to the diameter of the eye, which is contained 

 twice and two-thii-ds in the length of the head. Upper profile straight 

 above the occiput. Maxillary long and narrow, not extending to 

 below the middle of the eye. The origin of the dorsal fin is vertically 

 above that of the ventral ; the pectoral does not extend to the base 

 of the ventral. Light brownish, shining silvery ; caudal blackish, 

 with a pair of large reddish spots on its basal half. 



South America. 

 a. Four inches long. Presented by the Zoological Society. 



c. Cleft of the mouth of moderate width ; the entu-e edge of the maxillary 

 denticulated : Hemibrycon. 



32. Tetragonopterus polyodon. 

 D. 10. A. 27. V. 8. L. lat. 45. L. transv. 8/6. 



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

 out caudal), the length of the head two-ninths ; the upper profile 

 from the snout to the dorsal is gently cui'ved. Head compressed : 

 interorbital space convex, its width being equal to the diameter of 

 the eye, which is one-third of the length of the head ; snout shorter 

 than the eye, with the lower jaw prominent. The maxillary extends 

 beyond the front margin of the orbit. The origin of the dorsal fin 

 is midway between snout and root of the caudal, behind the ventral, 

 so that its hinder portion is above the anterior anal rays. The pec- 

 toral extends beyond the base of the ventral. Silvery, the middle 

 caudal rays black. 



Guayaquil. 

 a. Three and a half inches long. From Mr. Fraser's Collection. 



