91 



UNIO LIENOSUS. 



VARIETY CONSTRICTUS. 

 Plate XLIX.— Fig. 4. 



DESCRIPTION. 



Shell elliptical, ventricose; beaks rather prominent, 

 undulated, distant from the anterior margin; posterior 

 side furrowed, contracted at base; posterior angle 

 much above the line of the base; epidermis obscurely 

 rayed; within white; cardinal teeth robust. 



Cab. A. N. S., No. 20423. 



OBSERVATIONS. 



Inhabits North river, Rockbridge county, Virginia. 

 Several specimens of this variety exhibit the peculiar 

 groove on the posterior side, which has suggested the 

 name. In other respects it agrees with U. lineosus 

 of the south-western streams, except that the cardi- 

 nal teeth are more robust. 



UNIO STRAM1NEUS. 



Plate L. — Fig. 1. 

 DESCRIPTION. 



Shell ovate, ventricose; disk with coarse prominent 

 lines of growth; umbo with numerous undulated plicae; 

 umbonial slope undefined; ligament margin elevated; 



