52 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



conic ; bands of vomerine teeth separated by a rather broad area, each 

 confluent with the neighboring palatine band, the two forming a small 

 oblong patch much smaller than the eye, the division between the pala- 

 tine and vomer scarcely appreciable. p Palatine bands without backward 

 prolongation. Bands of teeth in jaws short and broad. Maxillary bar- 

 bel reaching about to middle of pectoral spine ; outer mental barbel to 

 base of pectoral ; inner slightly more than half head. 



Ante-dorsal shield short, crescent-shaped, a little more than three 

 times as broad as long on the median line. Occipital process sub-tri- 

 angular, its sides straight, slightly longer than broad, its median line 

 rather sharply keeled. Close in front of its base begins the deep fonta- 

 nelle, which is narrow and groove-like posteriorly, becoming rather 

 abruptly broader above the opercle, then gradually narrowed anteriorly. 



Ridges bounding fontanelle prominent anteriorly to a point just be- 

 hind vertical from nostrils, coarsely granular for their whole length, the 

 granules mostly arranged in one series. Between these ridges and the 

 eye on each side is another ridge extending obliquely backwards and 

 inwards from above front of eye, likewise very coarsely granular, the 

 granules mostly in two series. Shields of head all rough granular, the 

 granules forming irregular lines. Gill-membranes forming a narrow 

 fold across isthmus. 



Dorsal spine moderate, about equal to pectoral spine, 1^ in head. 

 Axillary pore present, small. Humeral process broad, scarcely granu- 

 lar, about two-fifths pectoral spine. Adipose fin rather long and low. 

 Caudal long, the upper lobe longest, somewhat longer than head. Anal 

 long and high, its outline emarginate, its longest rays a little more than 

 half head. Yentrals long, the vent nearer their base than that of anal. 



Color dusky, the entire ventral surface soiled with dark points ', fins 

 all largely blackish ; barbels black. 



Two specimens were obtained at Panama. This species may be known 

 at once by the four granulated ridges, which extend the length of the 

 interorbital space. 



SPECIMENS IN UNITED STATES NATIONAL MUSEUM. 



29400. Panama. Gilbert. 

 29478. Panama. Gilbert. 



18. Arius ftirthii Steindachner. 



A rius fiirthii Steindachner, Ichth. Beitrage, iv, 29, 1875 (Panama). 



Habitat. — Pacific coast of Central America; Panama. 

 This species is known to us only through the description of Stein- 

 dachner. 



19. Arius melanopus Giinther. 



Arius melanopus Giinther, Cat. Fish. Brit. Mns. 18G4, v, 172 (Kio Mot ago a; cast 

 coast of Guatemala) ; Steindachner, Ichth. Beitr. iv, 1875, 21) (Panama). 



Habitat. — Both (?) coasts of Central America ; liio Motagua ; Panama. 



