SOUTH AMERICAN XEMATOGNAHTI. 79 



Upper jaw longer; teeth all villiform; 

 vomerine teeth in two small ovate patches 

 which are separated from each other but 

 joined to the much larger palatine 

 patches. 



Gill-membranes forming a moderate fold across the 

 isthmus. Gill-rakers 5-1-12. 



Pectoral pore large; vertical series of pores present. 



Distance of dorsal fin from tip of snout 2^-2^ in the 

 length, the spine rather stout, If in head; its outer edge 

 granular toothed, its inner edge with short, recurved 

 teeth; distance of the adipose fin from the dorsal 3J-3^ 

 in the length; adipose fin slightly longer than high, 

 shorter than the dorsal fin. 



Caudal 4 in the length. 



Anal emarginate, little longer than high. 



Ventrals lf-2 in the length of the head. 



Pectoral spine IJ in head, its anterior margin granu- 

 lar toothed, its inner edge with long, straight teeth. 



Plumbeous, silvery below; fins dusky, inner surface of 

 ventrals and pectorals dark. 



Head 3f ; depth 5; D. I, 7; A. 18. 



One 2 .28 m. Panama. 



One $ .21 m. Panama. 



48. Tachisurus jordani. 



1 Arius assimilis Jordan & Gilbert (not of Gtinther) Bull. U. S. Fish 



Comm. 1882, 47 (Mazatlau). 

 Tachisurus jordani Eigenm. & Eigeum. Proc. Cal. Acad. 2d. Ser; vol. 



i, 1888, 142 (Panama). 



The specimens agree very closely with the description 

 of assimilis by Jordan & Gilbert. They differ in the 

 width of the mouth and in having a pectoral pore. 



Rather robust, the width little less than the depth; 

 caudal peduncle compressed. Head heavy, little broader 

 than high, its height 1| in its length, its width l|-ls, 

 width at the angle of the mouth 2-2^. Interorbital area 



