336 CYPRINODONTID^. 



Anal fin mucli smaller than, but commencing somewhat in advance 

 of, the dorsal. Ventral very small ; pectoral terminating at some 

 distance from the anal. Coloration uniform. (Oirard.) 

 Texas. 



6. Gambusia afl&nis. 



Heterandria affinis, Baird <5* Girard, Proc. Acad. Nat. Sc. Philad. 



1853, p. 890. 

 Garnbusia.affinis, Girard, U. S. lij- Mex. Bound. Ichth. p. 72, pi. 39. 



figs. 12-15. 



D. 6. A. 8*. 



The height of the body is scarcely more than the length of the 

 head, which is one-fourth of the total (without caudal). Origin of 

 the dorsal fin a little nearer to the extremity of the snout than to 

 that of the caudal fin. Anal fin similar to dorsal in size and in shape, 

 its origin being but little in advance of that of the dorsal. Ventrals 

 slender, extending considerably further backwards than the pectoral. 

 Dorsal and caudal more or less dotted with black. {Girard.) 



Texas. 



7. Gambusia gracilis. 



Xiphophorus gracilis, Hcckel, Sitzqshcr. Akad. Wiss. Wien, 1848, i. 

 part 3. p. 300, taf. 9. figs. 3-4. 



D. 8. A. 8-9. V. 6. L. lat. 29. L. transv. 7. 



The height of the body equals the length of the head, which is 

 one-fourth of the total (without caudal) ; in the female the body is 

 somewhat deeper. The origin of the dorsal fin is nearly in the mid- 

 dle of the total length, and but little behind that of the anal fin in 

 the female. Anal process of the male nearly twice as long as the 

 head, with the extremity bent. Pectorals reaching beyond the root 

 of the ventrals. Anal fin short in the female, the length of its base 

 being at least one-third of its distance from the caudal. A dark, 

 band runs from the upper end of the gill-opening to the caudal. 

 {Heck.) 



Orizaba (Mexico). 



8. Gambusia nicaraguensis. 

 D. 8. A. 10. L. lat. 29. L. transv. 8. 



The height of the body is contained thrice and a third in the total 

 length (without caudal), the length of the head thrice and two-thirds. 

 Snout broad, subspatulate, with the lower jaw projecting beyond the 

 upper. The diameter of the eye is a little more than the length of 

 snout, one-third of that of the head, and three-fifths of the width of 

 the interorbital space. In the female the origin of the dorsal fin is 

 somewhat nearer to the extremity of the caudal than to the end of 

 the snout, and opposite to the last ray of the anal fin. Pectoral fins 

 not quite reaching as far backwards as the ventrals, which terminate 

 immediately in front of the anal fin. Free portion of the tsCil rather 

 short, the length of the base of the anal fin being one-half of its dis- 

 * D. 7. A. 9, according to the figure. 



