19. TETRAGONOPTEEUS. 325 



total length (without caudal), the length of the head five times. 

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

 the eye, which is one-third of the length of the head. The upper 

 profile of the head is nearly straight. The maxillary does not extend 

 beyond the vertical from the front margin of the eye. The origin of 

 the dorsal fin is vertically above the hinder ventral rays. The pec- 

 toral extends on to the ventral. A silvery band along the side of the 

 body ; each caudal lobe with a blackish cross-band. (Kner.) 

 Bio Guapore, Rio Paraguay. 



17. Tetragonopterns brevimanus. 



i). 11. A. 21-23. L.lat. 38. L. transv. 6£/5|. 



The height of the body is one-third of the total length (without 

 caudal), the length of the head two-sevenths. Snout short and thick ; 

 interorbital space convex, its width being much more than the dia- 

 meter of the eye, which is nearly one-fourth of the length of the head. 

 The upper profile of the head is not concave. The maxillary extends 

 somewhat beyond the vertical from the front margin of the eye. The 

 origin of the dorsal fin is vertically immediately behind the root of 

 the ventrals. The pectoral does not extend to the ventral. A band- 

 like blackish spot on the root of the caudal fin. 



Guatemala. 



a-c. Adult. Yzabal. From the Collection of Messrs. Godman and 



Salvin. 

 d-f. Adult and half-grown. Rio S. Geronimo. From the Collection 



of Messrs. Godman and Salvin. 

 g-h. Half-grown. Guatemala. From the Collection of Messrs. 



Godman and Salvin. 



18. Tetragonopterns scabripinnis. 

 Jenyns, Zool. Beagle, Fish. p. 125. pi. 23. fig. 3. 



D. 10. A. 25. L.lat. 37-38. L. transv. 6/5. 



The. height of the body is one-third of the total length (without 

 caudal), the length of the- head two-sevenths. The upper profile of 

 the head is scarcely concave. The maxillary extends beyond the 

 front margin of the eye. The origin of the dorsal fin is vertically 

 behind the root of the ventrals. The pectoral extends beyond the 

 base of the ventrals. A dusky spot on the shoulder, another blackish 

 spot on the root of the caudal, both united by a silvery band. (Jen.) 



Rio de Janeiro. 



a-g. Adult and half-grown. Purchased of Mr. Cuming. 

 h-l. Adult and half-grown. Purchased of Mr. Frank. 



I am not quite certain whether these specimens are correctly re- 

 ferred to T. scabripinnis, although they are very closely allied to it. 

 They have a somewhat shorter head, the length of which is contained 

 thrice and three-fourths in the total (without caudal) ; the anal rays 

 vary from twenty-five to twenty-eight ; and there are seven scries 



