eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 459 



black spots, surrounded by pigmentless areas or with comet-like tails of pigment 

 cells. 



There is no doubt that the specimens from Barbados and Georgetown are 

 very similar. It is, of course, possible that they are specifically distinct. The 

 females are alike, and with the males so extremely variable it is not possible to 

 point out constant differences. 



306. Acanthophacelus bifurcus Eigenmann. (Plate LXV, figs. 4-6.) 



Acanthophacelus bifurcus Eigenmann, Ann. Carnegie Mus., VI, 1909, 52; Repts. 



Princeton Univ. Exp. Patagonia, III, 1910, 458. 



Type, a male, 22 mm. Christianburg. (Carnegie Museum Catalog of 

 Fishes No. 1088.) 



Cotypes, twenty-four females, the largest 29 mm. Small pond at Christian- 

 burg. (C. M. Cat. No. 1089a-e; I. U. Cat. No. 11763.) 



Cotypes, thirteen males, the largest 24 mm. Small pond at Christianburg. 

 (C. M. Cat. No. 1090a-e; I. U. Cat. No. 11764.) 



Cotypes, twenty-nine females, the largest 25 mm. Small creek at Wismar. 

 (C. M. Cat. No. 1091a-e; I. U. Cat. No. 11765.) 



Cotypes, eight males, the largest 24 mm. Small creek at Wismar. (C. M. 

 Cat. No. 1092a-6; I. U. Cat. No. 11766.) 



Some of the females only 20 mm. long are with young. 



Head 3.33-3.75; depth at origin of anal 4.5; depth of caudal peduncle 5.5; 

 D. 7-; A. 8; scales 26 or 27 to base of caudal; eye 2.5 in the head, 1.33 in the inter- 

 orbital; fourteen scales in front of the dorsal. 



Slender, much more so than Pcecilia vivipara; origin of dorsal about equi- 

 distant from base of middle caudal rays and occiput; end of anal below the vertical 

 from origin of the dorsal ; ventrals in the female reaching slightly beyond origin of 

 anal; pectorals to the ventrals. 



Females with a dark vertical spot on the upper part of the sides about six 

 scales behind the head, margined with lighter; dark borders of the scales of the 

 sides forming a regular reticulation; a black median line behind the anal; base 

 and tip of dorsal blackest, all the other fins hyaline. 



Male with the general color of the female, the dorsal nearly black; caudal 

 with a variously shaped, dark olive-green, vertical band at its base, usually con- 

 tinued into a long prong along the entire upper margin of the fin, very frequently 

 continued into a shorter prong along the ventral edge of the fin, the basal bar 

 sometimes diffused over the entire caudal peduncle; anal with some black. 



