78 CALIFORNIA ACADEMY OF SCIENCES. 



has a much stouter form, the dorsal and pectoral spines 

 more or less covered with a membrane, the pectoral 

 spine If in the head, the dorsal spine 1|; the granula- 

 tions of the head covered with skin and much less con- 

 spicuous than in the other examples; the space between 

 dorsal and adipose fins 4 in the length; the barbels all 

 thick and fleshy. 



47, Tachisurus seemanni, 



Arius seemanni Giinther, Cat. Fish. Brit. Mus. v, 147, 1864 (Central 



America); id, Fish. Cent. Am. vi, 1866, 393; Jordan, Proc. 



Phil. Acad. Nat. Sci, 1883, 282 (notes on type specimen). 

 Oaleichthys seemanni Jordan, Proc. U. S. Nat. Mus. 1885, 366 (name 



only). 

 Tachisurus seemanni Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. 



vol. i, 1888, 142 (Panama). 

 11 Arius assimilis Jordan & Gilbert, Bull. U. S. Fish Comm. 1882, 



47 (Mazatlan). (Not Arius assimilis Giinther.) 

 Habitat: West Coast of Tropical America. 



Body about as deep as wide, tapering to a slender 

 peduncle. Head flat, depressed in front, top of the 

 head coarsely granular; opercles smooth or with faint 

 striations; humeral process slightly granular, covered 

 with skin; the greatest depth of the head 1| in its 

 length, greatest width IJ-lf ; the width at angles of the 

 mouth 2J. Occipital process wider than long; foiitanel 

 open to above the posterior margin of the eye, with a 

 deep backward-extending groove. 



Interorbital area smooth, without ridges. 



Eye 2 in snout, 7 in head, 3|-4 in the interocular, 2J 

 in the interorbital. 



Maxillary barbels reaching slightly beyond base of 

 pectorals, mental barbels two-thirds toward the gill 

 opening, the postmentals half a diameter of the eye 

 behind the gill opening or farther. 



