90 THE CYPRINODONTS. 



median series on the flank as wide as the eye. Intestine short. A female of 

 an inch and a quarter contained twenty two embryos. 



Light olivaceous, yellowish to brownish, with seven to ten vertical bars of 

 brownish, separated by light or silvery spaces of equal width, on the sides of 

 the caudal portion, edges of scales darker, centres of scales in the median 

 series on the flank more or less silvery. Belly and lower surface of head 

 silvery to golden. The black of the inside walls of the abdomen shows 

 rather plainly on the outside. Occiput dark ; top of snout light. A dark 

 line between anal and caudal. Dorsal with a faint spot or group of puncti- 

 cnlations behind the middle near the base ; other fins plain to dark tipped. 

 Isthmus of Panama, fresh waters. 



HETERANDRIA. 



Eeterandria Agassiz, 1853, Am. Jour. Sci., XVI, 135, — 1S54, Am. Jour., XVII, 365,— Tenn. Riv. 

 Fish., 27. 



Girardinui (Part) Blk., 1860, Cypr., 481; Gth., 1866, Cat., VI, 351; Jor. & G., 1882, B. 16 U. S. 

 Mus., 318. 



Shape of the body similar to that of the Funduli, compressed, rather 

 elongate ; somewhat depressed on tlie head. Snout short, narrow. Chin 

 steep. Mouth small, narrow, very protractile ; mandibles longer, firmly 

 united ; intermaxillaries shorter. Teeth in bands, hooked, outer series 

 larger, firmly set, appearing slightly compressed or spear-shaped when seen 

 from front or rear. Gill membranes short, united, free from the isthmus. 

 Branchiostegal rays commonly five. Dorsal fin smaller and originating back- 

 ward of the anal. Anal opposed to dorsal in females, greatly advanced and 

 modified into an intromittent organ in the males. Ventrals small, more or 

 less modified in males. Scales large. Intestine medium to elongate. 



The species placed in this genus differ from those of Gambusia in the 

 shape of the teeth, the structure of the mouth, and in the number of bran- 

 chiostegal rays. Heterandria is still farther separated from Girardinus, 

 as is seen in the structure of the mouth, the dentition, the length of the 

 intestine, etc. 



The Carolinas to the Argentine Republic. 



