322 Fishes of Upper Georgia. 



The genera of our Cyprinodonts are in an extremely con- 

 fused state. The following is an attempt at an analysis of 

 their characters, as far as they can be ascertained, from the 

 literature of the subject : — 



♦Intestinal canal short, but little convoluted; bones of each mandib- 



ulary firmly united (carnivorous species). 

 a. Anal fin of the male not modified into an intromittent 

 organ. 

 b. Teeth in a single series, incisor-like, notched; dorsal 



nearly over ventrals ; form stout. . . Cytiuxodox. 



bb. Teeth all pointed ; ventrals present, 

 c. Teeth in a single series; dorsal in advance of anal. 



d. Dorsal and anal fins long (each with more than 20 



rays) Girakdixichthys. 



dd. Dorsal and anal fins short (each with 10 to 14 



rays) Lucaxia. 



cc. Teeth in narrow bands. 



e. Dorsal fin commencing in advance of anal. 



/. Brauchiostegals 6 HYDRvnGYRA. 



ff. Brauchiostegals 5 Fuxdulus. 



ee. Dorsal fin commencing directly over anal; both fins 



large; brauchiostegals 4; coloration peculiar. Xexisma. 

 eee. Dorsal fin commencing behind origin of anal; brau- 

 chiostegals 5. 

 g. Body small, short and thick, with broad head ; 



(subgenus?). • Micristiits. 



gg. Body elongate, slender, with narrow head. Zygoxectks. 

 aa. Anal fin of the male modified into a peculiar, sword- 

 shaped, iutromitteut organ; teeth pointed; dorsal fin 



short, behind anal Gambusia. 



** Intestinal canal elongated, with numerous convolutions; bones of 

 each mandibular^ not united, the dentary being movable; sexes 

 differentiated ; limnophagous. 

 h. Teeth pointed, in bands; dorsal in advance of anal, 



greatly developed'in $ (of more than 12 rays). Moli.iexesia. 

 hh. Teeth pointed, in a single series; dorsal behind anal, 



small (less than 12 rays) Girardixus. 



hhh. Teeth unknown; dorsal in advance of anal, small (less 



than 12 rays) Adixia. 



15. XENISMASTELLIFERA. Sp. nov. 

 Xenisma stellifera Jordan and Copeland, Check List (name only). 



This species — the type of the group called Xenisma — 



