BULLETIN OP THE UNITED STATES FISH COMMISSION. 51 



very short, ending obtusely at a point not far behind eye, the distance 

 from this point to tip of snout If in its distance from base of dorsal. 

 Each side of fontanelle with a conspicuous smooth ridge, the two ridges 

 converging anteriorly ; shields of head rather finely granulated, few of 

 the granulations forming lines, none of them extending farther forward 

 than posterior margin of eye. Opercle striate. 



Gill-membranes meeting below in a sharp angle, forming a rather 

 broad fold across isthmus. 



Dorsal spine very short, its length a trifle less than pectoral spine, 2\ 

 in head. Axillary pore obsolete. Humeral process granulated, rather 

 narrowly triangular, a little less than half length of pectoral spine, 

 which extends barely two-fifths the distance to the ventral fins ; adipose 

 fin long and low, very nearly or quite coterminous with the anal; caudal 

 narrow, rather short, the upper lobe longest, If in head ; anal rather 

 low and short ; ventrals short, the vent not far behind them. 



Color dusky above, pale below, the fins all more or less dusky; max- 

 illary barbels dusky, others pale. 



A single young male specimen was obtained at Panama. 



This is one of the more aberrant species of the genus. It is, however, 

 not distantly related to A. guatemalensis, and there is certainly no suffi- 

 cient ground for its separation from " Hexanematichthys" as a distinct 

 genus, " Leptarius" Gill. 



The original type of this species cannot be found. 



SPECEMEN IN UNITED STATES NATIONAL MUSEUM. 



29528. Panama. Gilbert. 



17. Ariua dasycephalus Giinther. 



Arim dasycephalus Giinther, Cat. Fish. Brit. Mus. v, 1864, 157 (Oahu, Sandwich 

 Islands) ; Steindachner, Ichth. Beitr. iv, 1875, 26 (Panama ; no description). 



EaMtat. — Tropical parts of the Eastern Pacific; *Sandwich Islands; 

 Panama. 



Head 4 J (5f) ; depth 6 (7±) ; width of head 5£; length (29400) 11 inches. 

 D.I, 7 j A. 4, 17. 



Body elongate, compressed behind, the head small, narrow and mod- 

 erately depressed anteriorly, the snout not very blunt. Eye rather large, 

 placed somewhat above level of angle of mouth, its length 5 in head ; 

 width of interorbital space 2^ in head; breadth of mouth 2£; length of 

 snout 3|. 



Teeth villiform, those of vomer and palatines rather coarse, bluntly 



* Three species (Arius dasycephalus, Ch&todon humeralis, and Isesihes brevipinnis), be- 

 longing to the fanna the Pacific Coast of Central America, are recorded by Dr. Giin- 

 ther from the Sandwich Islands. In these cases we strongly snspect that there has 

 been a confusion of localities among the specimens in the British Museum, and that 

 all came from America. 



