75 St. Maurice and Claiborne Pelecypoda 75 



margins crenulated ; posterior row of cardinal teeth verj^ short 

 (5 or 6) and making an angle of aboat 150° with the anterior ; 

 cartilage pit well marked and very oblique. 



Type and specimens figured. — Paleont. Museum, Cornell 

 Univ. 



Horizon and locality. — St. Maurice horizon, at the base of 

 the Upper Bluff at Claiborne, Ala. ; 3 miles W. N. W. of Orange- 

 burg, S. C. 



Certain small casts from a very light-colored, sandy compact, 

 clay, 6 miles W. N. W. of Orangeburg, S. C, seem also refer- 

 able to this species. The same kind of material shows the same 

 kinds of casts 5 miles N. of Orangeburg on Columbia Road. 



A very different form, more or less of the ovula type occurs 

 in Mississippi, but as our specimens are imperfect and the locality 

 is indefinite it seems inadvisable to assign a specific name to this 

 type (pi. 26, fig. 15). 



Nucula monroensis Aldrich, PI. 26. Fig. 11. 



M. monroensis Aid., Bull, i, Geol. Surv. Ala., 1886, p. 40, pi. 4, fig. 2. 



Aldrich' s original description. — Shell ovate-elliptical, subangular be- 

 hind, surface covered with raised, concentric ribs, sharp on the upper edge 

 and sloping down towards the ventral margin ; beaks recurved ; lunule 

 faintly marked, but large ; cavity of the shell rather deep ; margin cren- 

 ulated. 



Locality. — Calcareous sand-bed, lower part of Claiborne section, Mon- 

 roe County, Alabama. 



We have not had a specimen of this species for study but 

 owing to the extreme variability of these NttcidcB from the St . 

 Maurice beds we are prepared to see this shade into mauricensis 

 and even ripa and finally all into magnifica when a great amount 

 of material shall have been collected and studied. The type is 

 doubtless with the Aldrich collection in the Museum of Johns 

 Hopkins Univ. 



Nucula ovula Lea, PI. 26. Figs. 12-14. 



N. ovula Lea, Cont. to Geol., 1833, p. 80, pl. 3, fig. 59. 



