54 THE NAUTILUS. 



Symphynota costata Rafinesque. Tennessee river. Only dead 

 and poor ones found. 



Symphynota complanata Barnes. Tombigbee river, Columbus, 

 Miss. 



Margaritana monodonta Say. Tennessee river. Large numbers 

 were piled up by rocks, logs and in places on the river bank, where 

 the musk rats had opened them. The living ones were plen- 

 tiful under rocks in the shallow water, as many as two hundred 

 being found under one slab. 



Unio gibbapus Barnes. Tombigbee and Tennessee rivers. 



Unio crassidens Lam. Tombigbee and Tennessee rivers. 



Unio arctatus Conrad. Tombigbee river, Columbus, Miss. 



Unio tetralasmus geometricus Lea. Yalabusha river, Grenada, and 

 a rill near Durant, Miss. 



Pleurobema hohtonensis Lea. Tennessee river, Florence, Ala. 



Pleurobema edgariana Lea. Tennessee river, Florence, Ala. 



Pleurobema tumescens Lea. Tennessee river, Florence, Ala. 



Pleurobema dolabelloides Lea. Tennessee river, Florence, Ala. 



Pleurobema decisa Lea. Tombigbee river, Columbus, Miss. 



Pleurobema curta Lea. Big Black and Tombigbee rivers. 



Pleurobema taitiana Lea. Tombigbee river near Boligee, Ala. 



Pleurobema mix Lea. Tombigbee river, Columbus, Miss. 



Pleurobema bulbosa Lea. Tombigbee river, Columbus, Miss. 



Pleurobema nuculopses Conrad. Tombigbee river, Columbus, Miss. 



Pleurobema aesopus Green. Tennessee river, Florence, Ala. 



Quadrula asper Lea. Tallahatchie, Yalabusha, Big Black and 

 Tombigbee rivers. 



Quadrula plicata Say. Tennessee river, Florence, Ala. 



Quadrula perplicata Conrad. Yalabusha and Black rivers. 



Quadrula latecostata Lea. Tombigbee river, Columbus, Miss. 



Quadrula heros Say. Tallahatchie, Yalabusha and Tennessee 

 rivers. 



Quadrula trapezoides Lea. Yalabusha, Big Black and Tombigbee 

 rivers. 



Quadrula cylindrica Say. Tennessee river, Florence, Ala. 

 Quadrula tuetanevra Raf. Tombigbee and Tennessee rivers. 

 Common in botli streams. 



Quadrula intermedia Conrad. Tennessee river. 



Quadrula slopes Lea. Tombigbee river, Columbus, Miss. 



