PLATE CI 
PASS 
Figs, la, lb. OsTEEA trigonalis Conrad 381 
la. Exterior of lower valve. Greensboro. x % 
lb. Interior of the same valve. x % 
Pigs. 2-4. OsTREA cAROLiNENSis Conrad 381 
2. Interior of lower valve. Governor Run. x % 
3. Interior of upper valve. Same locality. x % 
4. Exterior of lower valve. Same locality. x % 
