318 Fretp Museum or Naturat History — Zoétoey, Vor. X. 
dividuals than others; sides with more or less distinct dark spots. In 
the specimens in which they are most distinct they form short, vertical 
bars, and in others they appear as quadrate spots. Dorsal fin with 
black chromatophores preceding each ray, forming a dark bar near the 
base; interradial membranes between the posterior rays of anal with 
black chromatophores, forming a dark spot at base of fin, these chro- 
matophores may or may not be extended on the rays and up the fin. 
All intergradations from an obscure spot at base of the rays to a promi- 
nent spot, with the black extending nearly to the tips of the rays, occur. 
A fairly common species on both slopes of Panama, occurring mainly 
in the upper courses of creeks. Numerous specimens are at hand. The 
FiG. 5. DISTAL PART OF INTROMITTENT ORGAN OF Gambusia episcopi Steindachner. 
(Greatly magnified.) 
largest female is 52 and the largest male 23 mm. in length. It was not 
taken in the Rio Tuyra or Rio Bayano basins. 
Further study of our material convinces us that the form we de- 
scribed as Gambusia latipunctata in 1913 intergrades with the present 
species and is therefore not valid. 
Habitat: Both slopes of Panama, north of the Rio Bayano. 
56. Gambusia cascajalensis Meek & Hildebrand. 
Gambusia cascajalensis Meek & Hildebrand, Field Mus. Nat. Hist. 
Pub., Zoél. Ser., X, 1913, 86 (Rio Cascajal, Porto Bello, Panama). 
Head 3.2 to 3.9; depth 3.7 to 4.5; D. 7 or 8; A. 10; scales 28 to 30. 
Body rather slender; the profile straight over the head, slightly 
convex from nape to dorsal; head rather flat above; snout moderate, 
3.1 to 3.35 in head; eye 2.8 to 3.25; interorbital 2.1 to 2.4; mouth rather 
small, the cleft extending about one-third the distance to eye; teeth in 
the jaws pointed, in bands, the outer ones slightly enlarged; scales 
moderate, cycloid, extending forward on snout and on base of caudal 
fin, 7 longitudinal rows between anterior part of base of dorsal and base 
of anal; caudal peduncle strongly compressed, its least depth 1.7 to 2 
in head; origin of dorsal in female over posterior rays of anal, and about 
midway between middle of eye and tip of caudal, in the male its origin 
