2g 2 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. X. 



Rcestes guatemalensis Eigenmann & Eigenmann, Proc. U. S. Nat. Mus., 



XIV, 1891, 56. 

 Rceboides guatemalensis Eigenmann & Eigenmann, Proc. U. S. Nat. Mus., 



XIV, 1891, 57; Jordan & Evermann, Bull. U. S. Nat. Mus., XLVII, 



1896, 338; Regan, Biol. Cent. Amer., Pisces, 1908, 174 (Rio Chagres); 



Evermann & Goldsborough, Proc. Biol. Soc. Wash., XXII, 1909, 



10 1 (Rio Boqueron; Tabernilla, Atlantic slope, Panama Canal 



Zone). 



Head 3.75 to 4.2; depth 2.65 to 2.95; D. u; A. 47 to 52; scales 82 to 

 89, rarely 80 or 81. 



Body deep, strongly compressed; the dorsal region elevated; profile 

 deeply concave over eyes in adult, less so in young; head small; snout 

 blunt, 3.34 to 4.5 in head; eye 3.1 to 3.8; interorbital 3.4 to 4.1; mouth 

 large; upper jaw projecting; maxillary reaching posterior margin of 

 pupil, 1.85 to 2.25 in head; premaxillary teeth in 3 more or less irregular 

 series; the first series composed of 4 conical teeth on outer edge pointed 

 directly outward, horn-like; the second series with pointed teeth, the 

 anterior ones in advance of lower lip; the third series composed of tri- 

 cuspid teeth; maxillary with about 6 small teeth on its inner anterior 

 angle and with from 5 to 8 blunt teeth on its outer margin; lower jaw 

 with 2 series, the first series with 2 conical teeth on outer margin pointed 

 directly forward, the second series anteriorly with 4 tricuspid teeth, 

 then with 2 or 3 smaller conical teeth at each side, then a larger tricuspid 

 tooth, this one followed by several minute, conical teeth; gill-rakers 

 rather short, 8 or 9 on lower limb of first arch; shoulder girdle with a 

 sharp spine, reaching base of pectorals; lateral line complete, straight; 

 scales small and thin; dorsal fin elevated anteriorly, its origin a little 

 nearer tip of adipose than tip of snout; adipose fin well developed, over 

 the base of about the eighth anal ray counting from the last ray forward; 

 caudal fin naked, the lower lobe the larger; anal fin very long, its origin 

 nearer tip of snout than the base of its last ray; ventral fins reaching 

 past origin of anal; pectoral fins overlapping the ventrals, not much 

 longer than the latter. 



Color greenish brown above, silvery below; a bright silvery lateral 

 band in which there is often a short longitudinal black bar under base 

 of dorsal. An obscure shoulder spot near upper angle of gill-opening 

 usually present; a large black caudal spot; pectorals greenish yellow; 

 other fins greenish at base, becoming red at tips. 



Of this species there are numerous specimens in the present collec- 

 tion, ranging in length from 40 to 150 mm. It is one of the most com- 

 mon fishes in the streams of the Atlantic slope of Panama, occurring 

 everywhere from brackish water upward to the mountain streams. 



