262 FISHES. 



of male often modified into a sword-shaj^ed intromitteni 

 organ; chiefly viviparous. 



Small fishes of fresh or brackish waters in both con- 

 tinents; most abundant in warm regions. Genera twenty- 

 five; species one hundred and twenty. A recently dis- 

 covered Cyprinodont {Protistius^ Cope) from S. A. is 

 said to have a rudimentary spinous dorsal fin, indicating a 

 close relationship between this family and the JPercesoces. 



Our numerous species are not well known, and the 

 current genera are but indifferently characterized. One 

 species {Girai'dinus formosus) from S. C. and Florida is 

 said to be the smallest known vertebrate. The species 

 here mentioned are carnivorous surface swimmers; many 

 southern species feed on mud and slime. 



* Intestinal canal short, but little convoluted; bones of each, 

 mandibilary firmly united; carnivorous species; anal fin not 

 modified into an intromittent organ ; ventrals present. 



f Teeth in a single series, incisor-like, notched; dorsal nearly • 

 over ventrals ; body stout and deep. Cyprinodon, 1. 



ff Teeth all pointed, in bands. 



a. Dorsal fin beginning in advance of anal. 



h. Branchiostegals 6 Hydrargyra, 2. 



hh. Branchiostegals 5. .... Fundulus, 3. 



aa. Dorsal beginning directly opposite anal ; both fins large; 

 branchiostegals 4 ; coloration peculiar. Xenisma, 4. 



aaa. Dorsal beginning behind origin of anal ; branchiostegals 

 5 Zygoxectes, 5. 



/. CYPRINODON, Lacepede. Mummichogs. 



1. C. variegatus, Lac. The common coastwise species, 

 enterinor streams. 



2. HYDRARGYRA, Lacepede. May Fishes. 



1. H. majilis, (Bloch & Schn.) C. & V. The common 

 coastwise speci(is — largest of our CyprUiodontidm. 



