17. MOLLIENESIA. 347 



line very indistinct. A round black spot on the middle of the side, 

 on the seventh and eight scales of the lateral line. 

 Eio Janeiro ; British Guyana. 



a-c. Females, 1^-2^ inches long. Rio Janeiro. Voyage of the 



' Herald.' 

 d. Female, 3^ inches long. British Guyana. Presented by Sir R. 



Schomburgk. 



15. Pceeilia punctata. 



Poecilia punctata, Cuv. Sf Val. xviii. p. 133. 

 D. 9. A. 6. L. lat. 31. 

 Tail elongate; anal high and pointed. Body with four or five 

 longitudinal series of small black spots. ( Val.) 

 Montevideo. Specimen 15 lines long. 



16. Pceeilia couchii. 



Limia couchiana, Girard, Proc. Acad. Nat. Sc. Philad. 1859, p. 116. 

 D. 9. A. 6. 



Known from females only. 



Body rather short, back convex. The length of the head is one- 

 fifth of the tocal (with the caudal) ; eye one- third of the length of 

 the head. Dorsal fin longer than high, its origin being nearer to the 

 root of the caudal than to the extremity of the snout ; its entire base 

 is placed on the posterior declivity of the back. Anal opposite the 

 hinder portion of the dorsal ; pectorals not extending to the ventral. 

 Brown, an obsolete blackish band along the side ; dorsal with a few 

 blackish spots, the other fins immaculate. (^Girard.) 



Rio San Juan (Province of New Leon.) 



17. MOLLIENESIA. 



Mollinesia, Lesueur, Journ. Ac. Nut. Sc. Philad. 1821, ii. p. 3. 

 Xiphopborus, sp., Heckel. 



Closely allied to Pceeilia. Cleft of the mouth small, transverse ; 

 mandible very short, with the bones not united, the dentary being 

 moveable. Snout not produced. Both jaws with a band of minute 

 teeth, those of the outer series being the largest and somewhat 

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

 of the dorsal in both sexes, the anal of the male being modified into 

 an intromittent organ. Dorsal fin large, larger in the male than in 

 the female, ^vith twelve or more rays. Intestinal tract with, nume- 

 rous convolutions. Mud-eating. 



Central America and southern parts of North America. 



The species may be subdivided thus : — 



a. Caudal of both sexes alike : MoUienesia, p. 348. 



^. The lower caudal rays of thfi male prolonged into a long, sword- 

 shaped appendage : Xiphnphonis, p. 349. 



