eigenmann: fresh water fishes. 279 



Suborder Percesoces. 



Cope, Trans. Am. Philos. Soc. XIV, 456. 



Ventral fins abdominal, with one spine and five soft rays ; gills and 

 mouth normal. 



Two of the families of this suborder have representatives in South 

 American fresh waters. They may be distinguished as follows : 



a. Ribs attached to strong parapophyses ; teeth small or wanting"; gill rakers long and slender ; 

 pectoral fins inserted high up. 



b. Pelvic bones free or connected with the clavicle by ligament ; carnivorous ; head elongate ; 



vertebrjE more than 35 ; dorsal spines slender, flexible, 1-8 in number; stomach not 



gizzard-like. AthainidcB. 



bb. Pelvic bones suspended from the postclavicles ; teeth feeble or absent, limnophagous ; 



head short and broad ; vertebrae about 24 ; stomach gizzard-like ; intestines very long. 



Miigilidce. 



The Miigilidce are chiefly marine, some enter or are permanently 

 established in fresh water, none are recorded from Patagonian fresh waters. 



Family VII. ATHERINID^. 



The Atherinidce, like the Mugilidce are chiefly marine. A number of 

 genera or species have become established in fresh water; thus species 

 of Atheriua and Menidia are established in fresh water in Cuba and 

 North America. Labidesthes is a genus confined to the fresh waters of the 

 eastern slope of the United States. LetJwstole and Cliirostoma are fresh- 

 water fishes of Mexico. Protistiiis is found in the Peruvian Andes at an 

 altitude of 12,000 feet ; Gasfropterus on the Pacific slope to an elevation 

 of 7,500 feet. 



Along the coast of Chili and Patagonia and entering its rivers or 

 established in its lakes are found several species of AtJierinopsis and 

 Menidia. 



The genera represented in the waters of Patagonia may be distinguished 

 as follows : 



a. Premaxillaries freely protractile, broad posteriorly, their edge strongly curved ; jaws nearly 

 equal, the lower slightly shorter, forming a pointed muzzle ; scales large, smooth ; first dorsal 

 rounded ; belly rounded ; anal about 14-19 ; teeth minute, in bands ; dorsal and anal naked. 



Menidia. 



aa. Premaxillaries not protractile, the skin of upper jaw mesially continuous with that of the 

 forehead ; teeth simple, pointed, in villiform bands ; vomer with teeth or not. Atheritiopsis. 



