296 Fretp Museum or Natural History — Zod ocy, VoL. X. 
Head 3.6 to 4.9; depth 3 to 3.65; D. 11; A. 32 to 37; scales in lateral 
series 70 to 8o. 
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 110 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 9g 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 
