SOUTH AMERICAN NEMATOGNATHI. 75 



iiig, not to base of pectoral; mental barbels not reaching 

 to edge of gill-membrane; postmentals to gill opening. 



Upper jaw considerably projecting; width of the mouth 

 2 in the head; teeth all villiform; the depth of the inter- 

 maxillary band 4 in its width; vomerine 

 patches of teeth small (the patch on one side 

 twice as large as on the other), and separ- 

 ated by a groove from the large sub-rhom- 

 boidal patches on the palatines. 



Gill-membranes meeting in an angle and forming 

 a fold across the isthmus. Gill-rakers 4-j-9. 



Pectoral pore none, vertical series of pores incon- 

 spicuous. 



Distance of the dorsal fin from tip of snout 2f in the 

 length, the dorsal spine equal to the length of the head, 

 granular in front and on the sides, minute teeth on its 

 inner margin, the first soft ray higher than the spine; 

 distance of the adipose fin from the dorsal 3| in the 

 length. Adipose fin more than twice as long as high, 

 as long as the dorsal fin, adnate. 



Anal emarginate, scarcely longer than high, the high- 

 est ray about 2 in the head. 



Ventrals reaching the anal, 1^ in head, the inner ray 

 Avith a dermal fold. 



Pectoral spine strong, curved, depressed, little shorter 

 than the dorsal spine, both margins with small, irregu- 

 lar teeth. 



Light brown, fins somewhat dusky. 



Head 4; depth 5^; D. I, 7; A. 18. 



A single specimen, $ .2Gm. Panama; Steindachner. 



This specimen differs from the description of the type, 

 but the difference may be due to the sex. 



45- Tachisurus elatturus. 



Arius elatturus Jordan & Gilbert, Bull. U. S. Fish Comm. 1882, 45 

 (Panama). 



