BULLETIN OF THE UNITED STATES FISH COMMISSION. 43 



Body comparatively elongate; the head small, rather narrow, de- 

 pressed anteriorly; the snout rather narrow and moderately rounded. 

 Eye moderate, placed well above mouth, its length ~>.\ in head. Inter- 

 orbital space flat and smooth, 2£ in head ; snout 3£; breadth of raouth 2. 



Mouth rather large, with thickish lips. Teeth villiform. Vomerine 

 bauds moderate, confluent with each other and with the much larger 

 ovate palatine bands; a slight constriction or furrow marking the 

 divisions. Palatine bands each with a backward prolongation. Pre- 

 maxillary band moderate. Barbels very short ; maxillary barbel scarcely 

 or not reaching to base of pectoral; outer mental barbel scarcely past 

 gill-opening below; inner shorter than snout. 



Ante-dorsal shield short, anteriorly truncate, not keeled, the length 

 on the median line about half of one of its halves. Occipital process 

 subtriangular, rather narrow, truncate behind, its margins straight, 

 becoming concave forward, its width at base about equal to its length ; 

 fontanelle an almost obsolete groove, its posterior end not reaching base 

 of occipital process by about the diameter of the eye; the groove extend- 

 ing forward to a point about midway between tip of snout and base of 

 dorsal spine. Anterior to this point is an equilateral triangle, flat, cov- 

 ered with smooth skin, the base of the triangle formed by the smooth, 

 flattish, interorbital area. Shields of head rather coarsely granular- 

 striate, the granulations beginning anteriorly about opposite posterior 

 margin of eye. Opercle scarcely striate. Gill membranes forming a 

 moderate fold across the isthmus. 



Dorsal spine high, about equal to pectoral spine, and but little 

 shorter than head. No axillary pore. Humeral process triangular, 

 granulated a little more than one-third length of pectoral spine. Adi- 

 pose fin rather long. Upper lobe of caudal longest, a little shorter 

 than head. Ventrals and anal moderate. 



Color brownish, not very dark; belly pale, thickly speckled with 

 brown; fins more or less dusky ; maxillary barbels black; mental bar- 

 bels pale. 



Two specimens were obtained at Panama. They disagree in several 

 details from Steindachner's description, and it is possible that they be- 

 long to a different species. The head in Steindachner's types is 3f to 

 3£ in length, and the occipital process is narrower and less widened an- 

 teriorly. 



SPECIMENS IN UNITED STATES NATIONAL MUSEUM. 



29417. Panama. Gilbert. 

 29500. Panama. Gilbert. 



9. Arius troscheli (Gill) Guntker. 



Sciades troschelii Gill, Proc. Ac. Nat. Sci. Phila. 1863, 1?1 (Panama). 



Arius troscheUi Gunther, Cat. Fish. Brit. Mus. v, 1804, 150 (copied from Gill). 



Habitat. — Pacific coast of Central America; Panama. 



This species is apparently related to, A. planiceps, &c, but on account 



