31 St. Maurice and Claiborne Pelecvpoda 31 



Pinna cawcawensis.n. sp., PI- i7- Figs, i, 2. 



General .shape and size indicated by fig. i ; .surface of the 

 valves with numerous radii above, well defined ; below with con- 

 centric undulations upon which are superimposed even more radi- 

 ating costse than above, but they are less di-stinct. Zigzag ba.ses 

 of fimbriate folds upon the ribs precisely as in the living sqiiawos- 

 issiinaVhW., or seminuda Lam. (pi. 16, figs. 12-13). 



In outline this is Xike jacksoniana Dall, or argcntea Con. 

 The Claiborne sand, Jackson and Vicksburg specimens, however, 

 .so far as our specimens show, had no well-developed dermal, 

 semicircular spines, and too, the radii on the lower portion of the 

 shell are fewer than above, and of uncertain direction. 



Type and specimens fii^iired. — Depo.sited in the Paleont. Mus. 

 Cornell Univ. 



Horizon. — St. Maurice Eocene. 



Locality. — Five miles N. of Orangeburg, Columl.)ia Road, 

 S. C. 



Pinna .sp. 



Several fragments of a Pinna ver}' similar in form to caurarv- 

 cnsis, argentea sxA jacksoniana are in our collections from the 

 Claiborne sand beds. Their .surface characters are too imperfect 

 to admit of specific description. 



Aldrich (Bull, i, Geol. Surv. Ala. 86, p. 49) refers to Pi)ina 

 "very large" at Coffeeville. Ala. 

 Modiolus cawcawensis, n. sp., PI. 17- Figs. 3, 4 



Specific characterization. — Size and form as figured; inflated 

 along a well defined umbonal ridge anteriorly, becoming le.ss ven- 

 tricose from the center of the shell posteriorly ; posterior broadl\' 

 and evenly rounded ; exterior with generally fine but more or 

 le.ss variable concentric lines of growth. 



In general outline this shell recalls N. dncatelii of Maryland 

 Miocene, but is broader po.steriorly and without the remarkable 

 concentric fold on the anterior of that species. 



It is far less angulated as to umbonal .slope and pcsterior ex- 

 tremity than cretacea of Conrad. 



