Dec. 28, 1916. Fishes of Panama — Meek and Hildebrand. 319 



is slightly nearer tip of caudal than tip of snout; caudal fin rounded; 

 anal fin in female inserted a little nearer tip of snout than tip of caudal, 

 the anterior rays somewhat produced; in the adult male the origin of 

 the anal is about equidistant from middle of eye and base of caudal, the 

 modified portion rather short, not nearly reaching base of caudal, its 

 structure as in G, episcopi; ventral fins reaching to or slightly past vent 

 in the female and well past the origin of the anal in the male; pectoral 

 fins reaching a little past base of ventrals, 1.2 to 1.5 in head. 



Color plain olivaceous; the dark pigment underneath the scales 

 marking the rows of scales, which are so prominent in G. episcopi, is 

 very indistinct in the present species; sides without spots or bars. The 

 tip of dorsal black; anal fin with a black spot at base, which is usually 

 extended on 2 to 5 rays of the fin. 



Of this species there are ntmierous specimens in the present collec- 

 tion. The largest female at hand is 62 and the largest male 43 mm. in 

 length. Only a few of our specimens are from the Pacific slope of Pana- 

 ma, and it appears to be comparatively rare in the Rio Chagres Basin, 

 but it is abundant in some small coastal streams at Porto Bello. It was 

 not taken in the Rio Tuyra or Rio Bayano basins. 



Habitat: Both slopes of Panama, north of the Rio Bayano. 



39. Genus Priapichthys Regan. 



Priapichthys Regan, Proc. Zool. Soc. London, 1913, 991 (type Gambusia 



annectens Regan). 



This genus differs from Gambusia in that the modified anal fin of the 

 male is longer, its tip nearly reaching the caudal fin, and it is differently 

 formed; the terminal part is hooked forward and the prolonged rays 

 taper distally and have no specially modified segments, except the usual 

 serrae of the posterior branch of the second; the first prolonged ray does 

 not extend to the apex, and the hook is supported by the anterior 

 branch of the second and third rays. (Regan) Origin of the dorsal 

 fin above the anal. We have tentatively referred one species {P. 

 panamensis), which does not possess definite antrorse hooks on the 

 intromittent organ, to this genus. 



KEY TO THE SPECIES. 



a. First produced ray of intromittent organ with a recurved spur 

 below its apex, directed upward and forward; the apex of this 

 organ curved forward; male with a jet black spot about the size of 

 pupil on sides slightly in advance of vertical from origin of dorsal; 

 dorsal with a dusky spot at base on posterior one-fourth of fin. 



