Dec. 28, 1916. Fishes or PANAMA— MEEK AND HILDEBRAND. 325 
pressed or pointed, curved inward, this series is followed by a narrow 
band of minute teeth; scales large, cycloid, 8 or 9 rows between base of 
dorsal and anal; origin of dorsal in female variable, usually about 
midway between end of snout and tip of caudal, and posterior to vertical 
from origin of anal; its origin in the male is at about the same point as 
in female, but the fin is higher; caudal fin scaly at base, its margin 
rounded; anal fin in female usually inserted about midway between tip 
of snout and base of caudal; anal fin in adult male inserted nearer end 
of snout than base of caudal, the modified portion very long, slender, 
more or less needle-shaped, 2.35 to 2.7 in length; ventral fins similar in 
both sexes, usually failing to reach vent in large females, reaching oppo- 
site base of anal in males; pectoral fins moderate, 1 to 1.25 in head. 
Color of sexes similar, olivaceous. Large specimens without cross- 
_ bars; young of 60 mm. and less in length with narrow, dark cross-bars 
on posterior portion of sides. Fins unmarked. 
Of this species we have 80 specimens. The largest female is 150 
and the largest male 60 mm. in length. It was taken by us only in 
brackish water about the city of Panama where it is fairly common. 
Fig. 9. DISTAL PART OF INTROMITTENT ORGAN OF Paciliopsis elongaius (Ganther). 
(Greatly magnified.) 
We have examined 2 female specimens, paratypes, of P. colombianus 
(Eigenmann & Henn). We do not find that they differ essentially from 
the present species. However, in the absence of male specimens of the 
former their identity with P. elongatus remains doubtful. 
Habitat: Pacific coast of Panama and probably of Colombia. 
62. Poeciliopsis isthmensis Regan. 
Paciliopsis isthmensis Regan, Proc. Zool. Soc. London, 1913, 997 
(Colon, Panama). 
Head 3.5 to 3.7; depth 2.5 to 3; D. 9 or 10; A. 10; scales 26 to 28. 
Body robust; mouth small; teeth in narrow bands; interorbital width 
1.8 to 2 in head; eye 3 to 3.2; origin of dorsal fin midway between 
anterior margin of the eye and base of caudal, its longest ray 1.5 in 
head; origin of anal below fourth or fifth ray of dorsal, its first branched 
ray 1.3 in head; pectoral a little shorter than the head; least depth of 
caudal peduncle 1.3 to 1.5 in head; in the male the origin of the dorsal is 
