296 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. X. 



Head 3.6 to 4.9; depth 3 to 3.65; D. n; A. 32 to 37; scales in lateral 

 series 70 to 80. 



Body elongate, compressed; profile straight or slightly concave over 

 eyes, slightly rounded in region of dorsal; head rather small; snout 

 pointed, 3.2 to 4 in head; eye 2.6 to 4.6; interorbital 2.18 to 3.6; mouth 

 moderate; upper jaw strongly projecting; maxillary usually not quite 

 reaching middle of eye, 2 to 2.35 in head; premaxillary teeth laterally 

 in only 2 series, anteriorly in 4 series, the fourth or transverse series 

 situated just in front of teeth in lower jaw, composed of 3 or 4 teeth ; the 

 series on outer edge of maxillary moderately developed, 12 or 13 in 

 number; teeth in lower jaw moderate, notably smaller than in B. 

 striatulus, 13 or 14, rarely only 12, in first series; gill-rakers rather small, 

 about 15 on lower limb of first arch; lateral line complete, curved down- 

 ward; scales rather small, more or less irregularly placed, 21 to 25 

 vertical rows between dorsal and adipose, 4 or 5 longitudinal rows 

 between lateral line and base of pectoral; dorsal fin inserted midway 

 between tip of snout and base of caudal, or slightly nearer the latter; 

 caudal fin forked, the lower lobe the larger; anal fin inserted behind 

 base of last ray of dorsal, its base notably longer than head; ventral 

 fins inserted a little nearer origin of anal than base of pectorals; pectoral 

 fins inserted under margin of operclei failing to reach base of ventrals 

 by 3 or 4 rows of scales in large examples, sometimes reaching ventrals 

 in the smaller ones. 



Color steel blue above, silvery below; a black bar on shoulder behind 

 margin of opercle; sides with ill defined blackish bars, these not evident 

 in specimens less than no mm. in length. The young with a dark 

 lateral band. A caudal spot present, or rarely wanting in large speci- 

 mens. Fins unmarked. 



This species is represented by many specimens, ranging from 25 

 to 500 mm. in length. It is very common in all streams in the Rio 

 Chagres Basin, ranging from the lowland waters to the highest mountain 

 streams. It is the most important fresh water food fish of Panama. 

 Its flesh is penetrated by numerous small bones, but it is of good flavor 

 and much prized by the natives. It is much more abundant than its 

 Pacific slope relative, B. striatulus. 



This species differs from B. striatulus principally in the denti- 

 tion. The scales are also a little smaller. The average in a lateral 

 series for the present species in 9 specimens is 74+, while in the 

 preceding species for the same number of specimens the average 

 is 68+. In the present species from 12 to 15 vertical rows of scales 

 cross the back, between the dorsal and adipose, while in the fore- 

 going there are 18 to 21 rows. The color in the present species 



