Henn: South American Pceciliid Fishes. 115 



the origin of the anal is very slightly nearer the tip of the snout than 

 the base of the caudal. Its length is one-third that of the entire length 

 of the fish. Pectorals nearly equal to the head, caudal rounded or oval. 

 Olivaceous, margins of each scale outlined with chromatophores. 

 Coloration more or less even throughout, except the belly, which is 

 white or colorless. Occiput chocolate-brown; a narrow median line 

 to dorsal, a similar line on the ventral keel of the caudal peduncle. 

 Operculum underlaid with silvery. In specimens less than 25 mm., 

 there are about ten, or fewer, narrow, indistinct, vertical lines of 

 darker, distributed between the head and caudal. All mature females 

 have a very conspicuous black area surrounding the vent. All of the 



fins are colorless. 



Genus Priapichthys Regan. 



Priapichthys Regan, Proc. Zool. Soc. London, 1913. P- 99i. text-fig. 170 B. 



Type, Gamhnsia annectens Regan. 



13. Priapichthys nigroventralis (Eigenmann & Henn.) 

 Gambusia nigroventralis Eigenmann & Henn, Indiana Univ. Studies, No. 16, 



1912, p. 26. (Rio San Juan at Istmina.) 

 Priapichthys nigroventralis Regan, Proc. Zool. Soc. London, 1913, p. 992- 

 Gambusia caudovitlata Regan, Ann. Mag. Nat. Hist., (8), XH, 1913, p. 47i (Rio 



Condoto of San Juan); Proc. Zool. Soc. London, 1913, p. 986. 



4835 a, C. M., Type, 4835 a-e, C. M.; 12689 «"/. I- U. M., paratypes. 



Istmina. Eigenmann. 

 6697 a-g, C. M.; 13613 I. U. M. Fifteen, four males, eleven females, 



15-25 mm. Tambo. C. E. Wilson. 



Fig. 3. Priapichthys nigroventralis (Eigenmann & Henn). Distal end of intro- 

 mittent organ. X — . No. 12,689, L U. M. Istmina, Colombia. 



13614, I. U. M. Four small specimens, 10-20 mm. Manigru. 

 Wilson. 



13615, I. U. M. One male, 21 mm. Quibdo. Wilson. 



6698 a-g, C. M.; 13616 I. U. M. Fifteen, seven males, eight females, 

 15-22 mm. Raspadura. Wilson. 



