Dec. 28, 1916. FisHes oF PANAMA— MEEK AND HILDEBRAND. 315 
“The distal segments of the first prolonged ray are produced into processes 
directed more or less towards its apex; the anterior branch of the second prol 
ray is slender distally and at some distance from the end has an antrorse projection 
state wiaie the termed the talbow’ ; the guetetion branch of this rey ends in a retroree 
ears OF Das, Gnd Sep Cemetary peor vo the elbcw of the 
anterior branch are produced into serra; third prolonged ray ends 
in a hook more or less similar to that of the second.” (Regan) 
The males of this genus and related genera are smaller than the 
females, and more elongate; they are apparently fewer in number. All 
Gambusia are small, and as a net sufficiently small to capture females will 
permit the males to pass through it, the few males taken by the 
collector may not indicate their true ratio. _Many of the species of this 
genus live in swamps and lowland streams, but a few species throughout 
Mexico and Central America are found in clear mountain streams at as 
high an altitude as any fishes are found. Gambusia feed chiefly on 
insects and small crustacea. To some of the species are credited the 
eating of mosquito larve. 
We here tentatively refer to this genus 2 species, G. episcopi 
and G. cascajalensis, that do not have any definite retrorse hooks 
on the distal portion of the intromittent organ, but they agree in 
other respects with this genus. 
KEY TO THE SPECIES. 
a. Intromittent organ of male with 2 strong retrorse hooks at apex, 
and anteriorly with strong serrations; each scale with a dark dot, 
forming lines along the rows of scales; dorsal and caudal with 
black spots, forming bars. nicaraguensts, p. 316. 
aa. ‘Intromittent organ of male without retrorse hooks or strong 
serrations at apex; no dark lines along the rows of scales; anal 
fin with a black spot at base, which may or may not be extended 
to tip of rays. 
b. Body rather robust, the depth 3.2 to 4.1 in length; caudal ped- 
uncle 1.15 to 1.6 in head; origin of dorsal in female over or 
slightly anterior to vertical from middle of anal; anal fin not 
falcate; skin underneath the scales strongly pigmented, mark- 
ing the margins of the scales; sides with more or less distinct 
dark spots or bars. Largest females 52 mm. in length. 
episcopi, p. 317. 
bb. Body slender, the depth 3.7 to 4.5 in length; caudal peduncle 1.7 
to 2 in head; origin of dorsal in female over posterior rays of 
anal; anal more or less falcate; the rows of scales very indis- 
tinctly marked; sides without spots or bars. Largest female 62 
mm. in length. cascajalensis, p. 318. 
