1010 MR. C. TATE REGAN ON 



jSTumerous examples, including co-types of the species received 

 from the Berlin Museum and the types of Girardinus guppyi ; 

 females to 55 mm., males to 25 mm., in total length. 



25. MoLLiENisiA Le Sueur, 1821, 



Journ. Acad. Philad. ii. p. 3 ; Giinth. Cat. Fish. vi. p. 347 

 (1866); Garman, Mem. Mus. Comp. Zool. xix. 1895, p. 49. 



This genus differs from PceciUa in having a small antrorse 

 spine at the end of the first prolonged ray of the male anal fin, 

 as in Limia, and at the end of the third a paired process, probably 

 the modified terminal segment, directed obliquely outwards and 

 towards the base of the fin, as in Lebistes (text-fig. 173 F). 



Some species hitherto referred to Pmcilia {M. sphenops, 

 M. gracilis) have an intromittent organ exactly similar to that of 

 Mollienisia latipinna and M. petenensis, and as the little-known 

 M.formosa is intermediate between the two groups in the size of 

 the dorsal fin, all may be placed in Mollienisia. Some other 

 species, with the dorsal fin further back than the anal, are pro- 

 visionally included ; all that is known of the males is Garman's 

 statement that in P. cuneata the anal fin of the male is shorter 

 than the head, indicating that the species is neither a Posciliopsis 

 nor a Girardinus, although it may be a Limia. 



Synopsis of the Species. 



I. Dorsal 11-16 ; in adult males origin nearer end of snout than 



base of caudal, base longer than distance from caudal. 



A. Caudal rounded or subtruncate (?) or lower angle slightly 



produced (^); scales 28 to 30. Dorsal 15-16 1. petenensis. 



B. Caudal rounded ; scales 26 to 28. 



Dorsal 14-16; in females origin equidistant from end of snout 

 aiid base of caudal (young) or nearer snout (adult) ; base equal 

 to (young) or more than (adult) distance from caudal 2. latipinna. 



Doi'sal 11-13 ; in females origin a little nearer base of caudal than 

 end of snout, even in the adult ; base equal to (adult) or less 

 than (young) distance from catidal 3. formosa. 



II. Dorsal 10-11 ; origin nearly equidistant from end of snout 



and base of caudal (in ; base sliorter than distance from 

 caudal ; anal origin below fourth ray of dorsal ; scales 28 

 to 30 4. gracilis. 



III. Dorsal 7-11 ; origin nearly eqiiidistant from end of snout 

 and middle or posterior end of caudal fin ; base shorter than 

 distance from caudal. 



A. Oi'igin of anal below or a little behind that of dorsal 6. sphenops. 



B. Origin of anal in advance of that of dorsal. 



Dorsal 8-10. Anal 8-10. Scales 29-33 Q. eloncjata. 



l)orsal7-9. Anal 9-11. Scales 27-30 7. oceidentalis. 



Dorsals. Anal 9. Scales 26 8. spihirvs. 



1 . Mollienisia petenensis. 



Giinth. Cat. Fish. vi. p. 348 (1866), and Trans. Zool. Hoc. vi. 

 1868, p. 485, pi. Ixxxvi. figs. 1-3 ; Regan, Biol. Centr.-Amer., 

 Pisces, p. 106 (1907). 



