69 



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

 (State Laboratory). 



Lampsilis leptodon Rafinesque { — tenuissima Lea). 



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

 kaskia River (Hinkley) ; Mississippi River, Mercer Co. 

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



Genus Obovaria Rafinesque. 



Subgenus Obovaria Rafinesque. 

 Obovaria retusa Lamarck. 



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

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

 rivers (Strode) . 

 Obovaria circulus Lea. 



Wabash River (Hinkley, Marsh) ; Southern Illinois (Ulffers). 

 Obovaria lens Lea. 



Ohio River (Hinkley, Marsh). 



Subgenus Pseudoon Simpson. 

 Obovaria ellipsis Lea. 



Northern Illinois; Illinois River (Calkins) ; Kankakee River 

 (Ferriss); Illinois River (Handwerk) ; Quincy, Adams Co. 

 (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 (Rafinesque) Agassiz. 



Subgenus Plagiola (Rafinesque) Agassiz. 

 Plagiola 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, Quincy, Adams Co. (Hart) ; Kas- 

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

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

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



*Calkins (Cin. Quart. Journ. Sci., I., p. 244) lists rUi/>.<<ix as occurring near Chicago, 

 but no authentic specimens have been seen, and occurrence of this species in the 

 Chicago region is very doubtful. 



