Synopsis Fresh-Watkr Moli^usca 17 



Key to the subfamilies of Ancylidcc. 



{ Shell patelliform 2 



[ vShell planorbiform or neritiform Neoplanorbince. 



f Shell and apex unicolored 3. 



[ Shell small, with pink apex Rhodacmemcc. 



f Shell large, apex submedial Lancincc. 



3- ! 



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



Subfamily LANCIX.^ 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 Lynnncra with two accessory plates. Radula also lymnseid 

 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 Laiicince. 



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: Aucyliis ncivberryi Lea, fig. 50. 

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



Fig. 50 



T'ig-5i 



