46 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



of them granular, the granulations chiefly confined to the region behind 

 widest part of fontanelle. Opercle striate. Gill -membranes forming a 

 moderate fold across isthmus. 



Dorsal spine low, shorter than pectoral spine, which is 1| in head, the 

 anterior edges of both bluntly serrate. Humeral process broadly tri- 

 angular, granulated, not two-fifths length of pectoral spine, much 

 smaller than in A. inscnlptus. No axillary pore. Adipose fin long and 

 low, without free posterior margin. Lower fins of moderate length; 

 vent much nearer ventrals than anal. Caudal short, the upper lobe 

 longest, If in head (a little more than half head inthe smaller specimens). 



Color dusky above, the lower parts soiled with dark points. Fins all 

 more or less dusky with dark points. Maxillary barbels dusky, others 

 pale. 



One male specimen was obtained at Panama. 



SPECIMENS IN UNITED STATES NATIONAL MUSEUM. 



29408. Panama. Gilbert, 

 30995. Panama. Powell. 



12. Arius osculus sp. nov. (29476.) 



Head 3£ (43); depth 6| (7§); width of head 4|; length (29476) 11 

 inches. D. I, 7; A. 4, 14. 



Body moderately elongate, the head short, rather narrow, tapering 

 forwards, considerably broader than deep. Eye small, 7 J in head, 

 placed well above the mouth. Interorbital space 1-^ in head; snout 3; 

 breadth of mouth 2f . 



Mouth very small for the genus, with thick lips. Teeth on vomer 

 and palatines villiform, but rather coarse and bluntish. Vomerine 

 patches small, rather longer than broad, separated on the median line, 

 and each also separated by a narrow groove from the large and roundish 

 palatine bands, which have a distinct backward prolongation. Premax- 

 illary band of teeth very broad, barely 3 times as long as wide. Barbels 

 short, the maxillary barbels reaching slightly beyond base of pectorals, 

 the outer mental barbels scarcely past gill-openiufFbelow; inner mental 

 barbels about as long as snout. 



Ante-dorsal shield short, crescent-shaped, granulated, but without 

 median keel, its length about one-fourth its breadth. Occipital process 

 narrow, its edges almost parallel until abruptly widened at base; the 

 narrow part considerably longer than broad, with curved edges. A 

 well-developed median keel. Fontanelle broad and shallow, abruptly 

 contracted at a point midway between tip of snout and end of occipital 

 process, thence continued backward as a narrow groove to a point less 

 than an eye's diameter in front of the base of the occipital process. 

 Greatest width of fontanelle about three-fifths eye. Shields cf top of 

 head all coarsely and rather sparsely granular, and anteriorly striate. 

 Interorbital space nearly plane, with a few low, smooth ridges. Opercle 



