DK. GUNTHER ON THE FISHES OF CENTRAL AMERICA. '485 



series of scales on each side of the tail. Lateral line rather indistinct. Greenish, each 

 scale with a black vertical spot. Dorsal and basal half of the anal irregularly and finely 

 marbled with brown. 



The male has the dorsal fin somewhat elevated, the longest ray being rather longer 

 than the head. Anal fin modified into an intromittent organ, and advanced to between 

 the ventrals, in front of the dorsal. Tail strongly compressed, and much higher than 

 in the female, its least depth being equal to the length of the head. 



Five examples, up to C inches in length, were collected by Mr. Salvin in Lake Peten. 



262. PCECIUA GILLII. 



Messrs. Kner & Steindachner (Abhandl. bayei-. Akad. Wiss. x. p. 25, Taf. 4. fig. 1) have 

 described a species of this genus from the Rio Chagres under the name of Xiphophorias 

 yillii. It would appear to be most closely allied to P. dovii ; but there are some appa- 

 rently slight differences, which have induced me to keep the two species distinct until I 

 shall have had an opportunity of comparing specimens from the Rio Chagres with the 

 typical examples of P. dovii. 



264. MoLLiENESiA PETENESsis. (Plate LXXXVL figs. 1-3.) 

 Giinth. Fish. vi. p. 348. 



B. 6. D. 15. A. 8-9. L. lat. 30. L. transv. 10. Vert. 17/13. 



The height of the body is one-third of the total length (without caudal), the length 

 of the head one-fourth or two-ninths. The diameter of the eye is equal to the length of 

 the snout, two-sevenths of that of the head, and rather less than one-half of the width 

 of the interorbital space. ' The length of the dorsal fin of the male is one-half of the 

 distance between eye and root of the caudal, in the female two-fifths ; caudal rounded, 

 with scales at the base only. The free portion of the tail is as high as long, and 

 covered by nine longitudinal series of scales on each side. Lateral line very indistinct. 

 Greenish, or brownish green, silvery below ; a dark spot to each scale of the upper and 

 middle caudal series and the lower part of the trunk. Dorsal fin of the adult male with 

 small irregular brown lines or spots, and with a row of large rounded spots along the 

 middle of its height. Interradial membrane of the caudal with numerous black dots ; 

 the lower part of the hind margin black. Females and immature males have the 

 dorsal fin simply ornamented with small irregularly curved brown spots. 



Three examples, up to 5 inches in length, were collected by Mr. Salvin in Lake Peten. 



Figure 1 represents the adult male, fig. 2 the immature male, and fig. 3 the adult 

 female, all of the natural size. 



265. XiPHOPHORUs HELLERii (Heck.). (Plate LXXXVIL figs. 2-6.) 

 This species varies considerably in coloration. Two varieties occur in the river 

 Chisoy — one with two yellowish green bands along the side, separated, and bordered 



