69 



ern Illinois (Ulffers) ; Fulton Co. (Wolf); Havana, Mason Co! 

 (State Laboratory). 



/.ai/ipsilis leptodon Ratinesque ( = teni(is.siina Lea). 



Savanna, Carroll Co. (Baker); Illinois River (Ferriss); Kas- 

 kaskia River (Hinkley) ; Mississi])pi River, Mercer Co. 

 (Marsh); Southern Illinois (Ulfters) ; Fulton Co. (Wolf). 



Genus Obovaria Rafinesque. 

 Subgenus Ohovaria Ratinesque. 

 Ohovaria retusa Lamarck. 



Northern Illinois (Calkins) ; Wabash River (Hinkley) ; La 

 Salle Co. (Huett) ; Ohio River (Marsh) ; Spoon and Illinois 

 rivers (Strode) . • • . ■ . 



Oboimrla circulus Lea. 



Wabash River (Hinkley, Marsh) ; Southern Illinois (Ulfl'ers). 

 Obovaria lens Lea. ' ■■ 



Ohio River (Hinkley, Marsh). , ' .; 



Subgenus Pseudoon Simpson, 



Obovaria ellipsis Lea. 



Northern Illinois : Illinois River (Calkins): Kankakee River 

 (Ferriss); Illinois River (Handwerk); (^aincy, Adams (3o. 

 (Hart); Wabash and Ohio rivers (Hinkley); La Salle Co. 

 (Huett); Mercer Co., Mississippi River (Marsh); Illinois and 

 Spoon rivers (Strode); Fulton Co. (Wolf); Illinois River, 

 Havana, Mason Co. (State Laboratory).* 



Genus Plagiola (Ratinesque) Agassiz. 



Subgenus PUujiola (Rafinesque) Agassiz. 



Phujiola securis Lea. • ' ■' ' 



Savanna, Carroll Co. (Baker) ; Northern Illinois (Calkins) ; 

 Kankakee River (Ferriss, Handwerk) ; Shawneetown, Gallatin 

 Co. (Fischer) ; Illinois River (Handwerk, Kelley, Nason, and 

 Strode); Mississippi River, <^uincy, Adams Co. (Hart); Kas- 

 kaskia, Wabash, and Ohio rivers (Hinkley); Mercer Co., Mis- 

 sissippi River (Marsh) ; Southern Illinois (Ultfers) ; Fulton Co. 

 (Wolf) ; Illinois River, Havana, Mason Co. (State Laboratory). 



*Calkins ((.'in. Quart. .lourn Sei., I., p. 244) lists cWipsi.v as occurrin}; near Chicago, 

 but no authentic specimens liave lieiMi wen, and occurrence of this species in tlie 

 Chicago region is very doubtful. 



