33 



angulated; beaks not prominent; ligament margin 

 short, elevated; within pale salmon colour; lateral 

 teeth slightly recurved. 



SYNONYME. 



U. lanceolatus, Lea. Trans. Amer. Philos. Soc, new series, 



vol. iii. pi. 3. fig. 2. 

 Cab. A. N. S. No. 1105. 



OBSERVATIONS. 



Inhabits Tar river, N. C, Mr. Lea. Mr. Hyde 

 has received specimens from the Rappahannoc at 

 Fredericksburg, Va. It approaches nearest in out- 

 line to U. productus and nasutus, but cannot be easily 

 confounded with either. 



UNIO RECTUS. 



Plate XV. 



DESCRIPTION. 



Shell profoundly elongated, thick; anterior side 

 short; posterior side rostrated, cuneiform; extremity 

 angular, compressed; umbo inflated, but not promi- 

 nent, obtusely rounded; disks slightly contracted in 

 the middle; ligament margin nearly rectilinear; epi- 

 dermis dark green or olive-brown, smooth, frequently 

 with broad green rays; within pink in the middle; 

 cardinal teeth small, direct, double in each valve. 



SYNONYMES. 



U. rectus, Lam. An. sans vert. vol. vi. p. 74. 

 E 



