G6 



On Two new Cyprinodont Fishes. 



tlie end of the third and the posterior branch of the second 

 ])rolonged rays are small, also as in Beloneso.v, but the ante- 

 rior branch of the second has the " elbow " seen in all the 

 species of Gambusia. 



Heteropliallus rachovii, sp. n. 



Depth of body 3 to 3| in the length, length of head 4. 

 Diameter of eye 3 in the length of head, interorbital width 2. 

 30 scales in a longitudinal series. Dorsal 7, entirely behind 

 anal ; origin twice as distant from snout {^) or eye (?) as 

 from base of caudal ; fin rather elevated, in males reaching 

 to within a short distance of the caudal when laid back. 



A. B. 



Extremity of iutromittent organ of A. Heterophallus rachovii, 

 B. Gambusia yucatana. 



The first, second, and third prolonged rays are numbered 1, 2, 3. 



Anal 10; free edge straight or a little convex. Pectoral as 

 long as head. Caudal rounded. Olivaceous ; a dark line 

 along side of body; dorsal with a dusky intramarginal 

 band. 



Vera Cruz. 



Six s[)eciniens (3 J, 3 ? ) up to 35 mm. in total length. 



