262 FISHES. 



of male often modified into a sword-shaped intromittent 

 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 Percesoces. 



Our numerous species are not well known, and the 

 current genera are but indifferently characterized. One 

 species (G-irardinus 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. 



ft Teeth all pointed, in bands. 

 a. Dorsal fin beginning in advance of anal. 



b. Branchiostegals 6 HYDRARGYRA, 2. 



bb. 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 ZYGONECTES, 5. 



/. CYPRINODON, Lacepede. MUMMICHOGS. 

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

 entering streams. 



2. HYDRARGYRA, Lacepede. MAY FISHES. 

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

 coastwise species largest of our Cyprinodontidce. 



