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 (Qirardinus 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. CYPIUNODON, 1. 



ff Teeth all pointed, in bands. 

 a. Dorsal fin beginning in advance of anal. 



b. Branchiostegals 6 HYDRAROTRA, 2. 



bb. Branchiostegals 5 FUNDULUS, 3. 



act. 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. variegatus, Lac. The common coastwise species, 

 entering streams. 



2. HYDRARGYRA, Lacepede. MAY FISHES. 

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

 coastwise species largest of our Cyprinodontidce. 



