I. 



Synopsis Fresh-Water Moei^usca 17 



Key to the subfamilies of Ancylidce. 

 { Shell patelliform o 



1 . . 



[ Shell planorbiform or neritiform Neoplanorhincs. 



{ Shell and apex unicolored -i 



i ■^' 



[ Shell small, with pink apex Rhodacmeino'. 



{ Shell large, apex siibmedial Lancincc. 



Shell small, apex more or less posterior and excentric. . .Ferrissiince. 



Subfamily LANCIN^B Hannibal, 1914. 



Shell large for the family, ovate-elliptical, depressed or roundly arched ; 

 apex submedial, not prominent, smooth or concentrically striate. Animal 

 with the jaw as in Lymncca with two accessory plates. Radula also lymnasid 

 in character. Central tooth unicuspid Or tricuspid; laterals bicuspid with 

 large quadrate bases; marginals comb-like, the cusps extending beyond the 

 base. 



Key to the genera of Lancince. 



Shell larger, apex subcentral .Lanx. 



Shell smaller, apex subterminal Fisherola. 



Genus LANX Clessin, 1880. 



Shell large, broadly ovate, roundly arched, rather 

 solid, apex not prominent, smooth or concentrically 

 striate, subcentral. Radula as in the subfamily. 



Type: Ancylus nezvberryi Lea, fig. 50. 

 Radula: Lanx pattelloidcs (Lea), fig. 51. 



Fig- 50 



I^^i"g-5i 



