262 Pishes. 



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 Gyprinodont {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 indiiferently 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 fln not 

 modified into an intromittent organ ; ventrals present. 

 t 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. 



b. Branchiostegals 6 Htdbabgtra, 2. 



hb. Branchiostegals 5 FnNDTn.TJS, 3. 



CM. Dorsal beginning directly opposite anal ; both flns large ; 



branchiostegals 4; coloration peculiar. Xenisma, 4. 



aaa. Dorsal beginning behind origin of anal ; branchiostegals 



5 Zygonectbs, 5. 



/. CYPRINODON, Laoepede. Mttmmichogs. 

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

 entering streams. 



2. HYDRARGYRA, Lacepede. Mat Fishes. 

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

 coastwise species — largest of our Gyprinodontidce. 



