PLATE XXXIII. 



Page 



Unio Roanokoides Lea ^48 



Fig. 1. Left view of a speciineu of tlie prevailing form. 



2. Left view of another specimen, showing less arciiatiou of the hinge-line and a 

 more quadrangular form. See outline, Fig. 3, Plate XXXI. 



Unio ala^toides Lea 249 



Fig. 3. View of a specimen of this .species, showing a portion of the jiosterior alation. 

 4. View of another specimen differing iu size and iu the curvature of the basal line. 



334 



