THE CYPRINODONTS. 51 



ventrals on males. Ventrals small, second ray elongate in the male. Pec- 

 torals moderate, reaching a vertical from the bases of the ventrals on females 

 or behind the anal on males. Caudal deep, median rays longer. Scales large, 

 broad, short. Intestine long. 



Olivaceous to greenish or yellowish, silvery to white below. Commonly 

 each scale on flanks and back is marked with a dark spot on its middle ; 

 these spots are more or less confluent into lines. Variations in maculation 

 and in the markings of the fins are shown on Plate XII. In life the males 

 are likely to be tinted with bluish and yellow. Frequently the sides of the 

 head, the middle of the caudal, and the edge of the dorsal are yellow. Karely 

 upper and lower edges of the caudal are black. Many have vertical bands 

 on the flanks. Occasional specimens are blotched with black somewhat as 

 appears in the figures of Gamhusia HolhrooJiii, Plate XI. Fig. 4 and 5. The 

 larger, more elongate spots on the dorsal of the male are usually edged 

 with bright color. The ground color of the fin varies from bluish to yellow. 

 Figure 9 of Plate XII. represents a male at the period of greatest sexual 

 variation in shapes and markings. The largest individual of this sex at 

 hand measures three and seven eighths inches. 

 Virginia to Mexico. 



MoUienisia petenensis. 



MoUieimia petenensis Gth., 1866, Cat., VI, 348, —1868, Tr. Zool. Soc. Loud., VI, 485, pi. 86, fig. 

 1-3 ; Eig , 1893, P. U. S. Mus., XVI, 57- 



B. 6 ; D. 15 ; A. 8-9 ; LI. 30 ; Ltr. 10 ; Vert. 30. 



Height one third, and length of head one fourth or two ninths of the 

 length to the base of the caudal. Eye equal length of snout, two sevenths 

 of head, rather less than half of interorbital space. Length of dorsal in 

 male equals half the distance from eye to root of caudal, in female two fifths. 

 Caudal rounded, base scaly ; pedicel as deep as long, with nine series of 

 scales along each side. Lateral line 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 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 caudal with numerous black dots ; lower part of margin black. Dor-sal 

 on females and immature males simply ornamented with small irregularly 

 curved brown spots. 



Lake Peten. (Glinther.) 



