PLATE CVI. 
PAGE 
Figs. 1. 2. Arca (Scapharca) idoxea Conrad 389 
1. Interior of left valve. St. Mary's River. 
2. Exterior of right valve. Same locality. 
Figs. 3, 4. Arca (Noetia) incile Say 390 
3. Exterior of right valve. Darlington, South Carolina. Johns 
Hopkins University. 
4. Interior of left valve. Same locality. 
Figs. 5, 6. Arca (Barbatia) oentexaria Say 391 
5. Interior of right valve. Jones Wharf. 
6. Exterior of left valve. Same locality. 
Fig. 7. Arca (Barbatia) mahylandica Conrad 392 
7. Exterior of right valve. Plum Point. U. S. National Museum. 
Fig. 8. Arca (Barbatia) vir(11.ni.e Wagner 392 
8. Exterior of left valve of type specimen. Miocene of Virginia 
(Nansemond River?) 84 mm. Wagner Free Inst. Sci. (After 
Dall.) 
