DR. 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 6 inches in length, were collected by Mr. Salvin in Lake Peten. 
262. Pascua GILLI. 
Messrs. Kner & Steindachner (Abhandl. bayer. Akad. Wiss. x. p. 25, Taf. 4. fig. 1) have 
described a species of this genus from the Rio Chagres under the name of Xiphophorus 
gillt. It would appear to be most closely allied to P. doviz; 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. dovit. 
264. MOLLIENESIA PETENENSIS. (Plate LX X XVI. 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. X1iPHOPHORUS HELLER (Heck.). (Plate LXXXVII. 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 
