3io FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. X. 



Body elongate, compressed; size small; head short; snout blunt; 

 frontal and parietal fontanels well developed; mouth small; teeth 

 wanting; eyes covered by a transparent membrane; scales small, cycloid; 

 lateral line complete; no caudal fin; origin of anal about the length of 

 pectoral fin behind vertical from gill-opening. 



51. Hypopomus brevirostris (Steindachner). 



Rhamphichthys breviroslris Steindachner, Sitzb. K. Ak. Wiss. Wien, 



LVIII, 1868, 254, PI. II, fig. 2 (Guapore"); Gunther, Cat. Fish. 



Brit. Mus., VIII, 1870, 6; Steindachner, Denkschr. K. Ak. Wiss. 



Wien, XLI, 1880, 89 (Rio Guapore", Amazon stream near San- 



tarem, and Rio Cauca). 

 Brachyrhamphichthys brevirostris Eigenmann & Eigenmann, Proc. 



U. S. Nat. Mus., XIV, 1891, 62. 

 Hypopomus brevirostris Eigenmann & Kennedy, Proc. Ac. Nat. Sci. 



Phila., 1903, 530 (Campo Grande, Arroyo Chagalalina) ; Ellis, 



Memoir. Carnegie Mus., VI, 1913, 134, fig. 7; Eigenmann & Fisher, 



Indiana Univ. Studies, No. 25, 1914, 236 (Rivers of Colombia). 

 Hypopomus occidentalis Regan, Ann. & Mag. Nat. Hist., Ser. 8, XIV, 



1914, 32. 



Head in length to end of anal fin 6.8 to 9.3; depth 6.8 to 9; A. 213 to 

 238. 



Body elongate, rather strongly compressed; caudal filament ribbon- 

 shaped, pointed; upper profile of head and body gently convex; head 

 short; snout blunt, 3 to 3.55 in head; eye small, covered with a trans- 

 parent membrane, 9 to 12 in head; interorbital 4 to 4.35; mouth small; 

 jaws subequal, the lower slightly included; maxillary about twice the 

 length of eye; teeth wanting; no mental filaments; lateral line becoming 

 obscure posteriorly; scales small, cycloid; caudal filament 1.12 to 1.2 in 

 length to end of anal; vent under preopercular margin, from 2 to 3.5 

 times diameter of eye behind vertical from posterior margin of orbit; 

 origin of anal fin a little in advance of tips of pectorals, or about the 

 snout's length behind base of these fins; pectoral fins short, 1.65 to 2 in 

 head. 



Color brownish or buff, with darker markings of varying sizes, some- 

 times forming more or less distinct cross-bars on anterior portion of 

 body. 



This fish is represented by 4 specimens ranging from 68 to 162 mm. 

 in length. Two of our specimens are from the Rio Chagres Basin and 

 the other two from the Rio Bayano Basin. 



Habitat: Both slopes of Panama and Colombia and south to the 

 Rio de la Plata. 



