_— Weve 
? —'* 
> 
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. Rarely 
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 Gambusia Holbrookii, Plate XI. Fig. 4 and 5. The 
THE CYPRINODONTS. 51 
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. 
Mollienisia petenensis. 
Mollienesia petenensis Gth., 1866, Cat., VI, 348, —1868, Tr. Zool. Soc. Lond., VI, 485, pl. 86, fig. 
1-3; Eig., 1893, P. U. S. Mus., XVI, 57. 
B.6; D. 15; A. 8-9; Ll. 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. Dorsal 
on females and immature males simply ornamented with small irregularly 
curved brown spots. 
Lake Peten. (Giinther.) 
