GENERA OF ATHERINOPSIN^-E 17 



caudal ; end of second dorsal over that of anal ; 

 rami of mandibles elevated posteriorly. Shores of 

 tropical Pacific 25. Thyrinops. 



dd". Scale margins all sharply and strongly dentate; apical 

 radii obsolete ; belly longer, the origin of the anal fin 

 being nearer caudal base than head; end of short 

 second dorsal well behind that of anal; rami of man- 

 dibles highly elevated posteriorly; the ventral com- 

 pression of the body carried to the extreme, the belly 

 forming a keel both before and behind ventrals. 



Shores of the tropical Pacific ....26. Atherinella. 



y. Head truncated posteriorly, the opercle shorr ; preopercular 



ridge with a weak flat spine at angle ; interorbital convex ; 



head and body sharply compressed, especially ventrally ; 



rami of mandibles scarcely elevated posteriorly ; silvery 



lateral band very wide. Shores of the tropical Pacific- 



27. EURYSTOLE. 



X'. Scales of small or moderate size, in 48 to 105 series ; pectoral 

 fins usually not reaching to vertical from insertion of ven- 

 tral ; fishes of larger size. Temperate ivaters of South 

 America, ranging northzvard to southeastern Brazil and to 

 Peru, 

 ee^. Body of the form, and with the sharply compressed belly, 

 of Thyrina ; scales in 53 series, their margins laciniate; 

 teeth lacking on vomer, in two series on jaws; first dorsal 

 anterior to anal ; pectorals reaching to vertical from 

 insertion of ventrals. Southeastern Brazil in fresh zvater. 



28. Pseudothyrina. 



ee^. Body of the form, and with the rounded belly, of Menidia ; 



pectorals not reaching to ventrals. 



//i. Scale margins sublaciniate ; teeth well developed on 



the vomer, in bands on jaws ; first dorsal inserted over 



anus. Southeastern Brazil, in fresh water. 



29. Kronia. 

 ff. Scale margins entire, so far as known. 



gg^. Head pike-like, sharply pointed ; belly greatly 

 lengthened, the dorsal and anal fins located pos- 

 teriorly ; first dorsal base over origin of anal ; teeth 

 well developed on vomer ; scales in about 50 to 70 



series. Argentina 30. Odontesthes. 



gg'. Head formed as in Menidia ; belly less lengthened, 

 the dorsal and anal fins less posterior ; first dorsal 

 base over interspace between insertion of ventral 

 and origin of anal ; teeth usually lacking on vomer ; 

 scales usually finer. Shores and streams of Argen- 

 tina, Peru, and Chile 31. Austromenidia. 



W-. Teeth obsolete, or microscopic and deciduous ; scales small, 

 in about 70 series, their margins serrulate ; lower jaw deep at 

 base ; first dorsal fin over front of anal. Shores of California 

 and the outer coast of Lozver California 2>3. Leuresthes 



