BULLETIN OF THE UNITED STATES FISH COMMISSION. 3D 



U. Fontanelle not prolonged backward in a groove: bases of 

 paired fins pale ; body slender ; caudal about as long a* 



head GtJATEMALENSIS, 15. 



kk. Interorbital area with smooth ridges; lins very small, the 

 spines less than half head; fontanelle very short, not 

 prolonged in a groove behind ; gill-membranes meeting 

 in an angle; shields snioothish; vomerine bands separ- 

 ate; barbels extremely long; bead 4 in length; body 



very slender DOWI, 16. 



kick. Interorbital area with four very rough granulated ridges; 

 shields of head coarsely granular; vomerine and pala- 

 tine teeth on each side confluent in a small roundish 

 patch; gill-membranes not forming an angle; fonta- 

 nelle prolonged backward in a groove ; spines higb ; 



head 4^ in length Dasyckphalus, 17. 



jj. Teeth on vomer and palatines granular (Arius C. & V.) ; shields 

 not very rough ; fontanelle groove-like posteriorly, 

 o. Vomerine teeth coarse, the patches near together ; ven- 



tralspale; head 3f in length Fckthi, 18. 



oo. Vomerine teeth small, the patches widely separated; 

 ventrals jet-black on the inner margin; head 3£ in 



length Melanopus, 19. 



hh. Eyes placed very low, not above the level of the angle of the mouth 

 (Cathorops J. & G.). 

 p. Body slender, compressed ; shields of head rugose 

 rather than granular ; fontanelle groove-like posteri- 

 orly, interorbital area with smooth ridges ; fins high ; 

 jaws thin, with thin lips ; teeth on palate bluntish- 

 conical, forming two large patches, separated on the 

 median line by a very wide space ; barbels long. 



Hypophthalmus, 20. 



4. Arius alatus Steindachner. 



Arius alatus Steindachner, Ichth. Beitr. iv, 19, taf. vi, 1875 (Panama); Steind- 

 achner, Zur Fisch-Fauna des Cauca unci der Fliisse bei Guayaquil, 1880, 45, 

 taf. v f . 2 (Guayaquil). 



Habitat. — Pacific coast of Tropical America; Panama; Guayaquil. 

 This species is known to ns only from the accounts given by Dr. Steind- 

 achner. 



5. Arius brandtii Steindachner. — Bagre Colorado. 



Arius brandtii Steindachner, Ichthyol. Beitriige, iv, 21, taf. iii, 1875 (Altahi; 

 Panama). 



Habitat. — Pacific coast of tropical America ; Mazatlan; Altata; Punta 

 Arenas ; Panama. 



Head 3J (3f) ; width of head 4^ (4f ) ; depth 5 (6£) ; length (28230) 

 24 inches. D. I, 7; P. I, 12 ; A. 3, 16. 



Body comparatively robust, broad anteriorly; head not much de- 

 pressed, broader than high ; eye moderate, 7 to 8 times in length of head; 

 width of interorbital space If; breadth of mouth If; length of snout 3 J. 



Teeth all villiform; band of vomerine teeth simple, trapezoidal, quad- 

 rangular, longer than broad, without division on median line; baud of 

 palatine teeth very large, each separated in young specimens from the 



