350 CTPBINODONTID^. 



vated in males. Caudal fin roimded, with the basal third scaly ; the 

 lower rays of the caudal fin of the male are produced into a long 

 sword-shaped appendage which in the adult is nearly as long as the 

 body of the fish. Ventral immediately below the origin of the dorsal 

 in both sexes. Anal of the male modified into an intromittent organ, 

 one or two of the enlarged rays having several hook-like processes 

 at their extremities. The free portion of the tail is two-thirds as 

 high as long in males, and a little lower in females. Lateral line 

 indistinct. Caudal appendage of the male yellow, "with black edges. 

 Central America. 



Var a. 

 Two yellowish -green bands along the side, separated, and bor- 

 dered above and below, by a blue band. 



a-b, c-d. Males and females. River Chisoy. From the Collection 



of Messrs. Godman and Salvin. 

 e. Male : skeleton. River Chisoy. 



Var. (3. 

 The middle blue band darkest, black, running from the eye to, 

 and along the upper border of, the caudal appendage. 



/, g-l. Adult males. Cordova. 



m. Halfgrown male. Mexico. From M. Salle's Collection. Caudal 

 appendage very short. 



Var. y. 

 Body without bands, covered all over with irregular black spots. 



n~q. Males. River Chisoy. From the Collection of Messrs. God- 

 man and Salvin. 



18. PLATYPCECILUS. 



Cleft of the mouth small, transverse, mandible very short, with 

 the bones not united, the dentary being moveable. Snout not pro- 

 duced. Both jaws with a single series of small, pointed teeth. 

 Scales rather large. Origin of the anal fin behind that of the dorsal. 

 Sexes drfferentiated ? Intestinal tract "with numerous convolutions. 

 Mud- eating. 



Central America. 



Although we know only the female of this fish, we conclude, from 

 its close affinity to Poecilia and Mollienesia, that the anal fin of the 

 male is similarly modified. 



1. Platypcecilus maculatus. 

 D. 10. A. 9. V. 6. L. lat. 25. L. transv. 8. 

 Body much compressed and elevated, its greatest dej)th being 

 below the origin of the dorsal fin, and contained twice and one- 

 third in the total ("without caudal). Head less compressed than the 

 body, the width of the interorbital space being neaily two-thirds of 

 the length of the head, which is two -sevenths of the total (without 



