113 St. Maurice and Claiboiink Pelecypoda 113 



Claiborne stages one notes at once the presence of the new, or 

 non-Sabine form, L. dolabra. It has practically no resemblance 

 to anything seen before in the American Eocene deposits. 



One marvels at the scarcity of little Lucinas in the vast 

 stretches of St. Maurice deposits of the Gulf border states. 



The generally lignitic conditions of the Claiborne stage, 

 however, bring back the bulk of the small Lucinas that had ap- 

 peared just at the close of the Sabine. For Vv^ant of better names, 

 the three commoil stocks may be named the (i) smithi, (2) ul- 

 richi (Har. non Clark) and the (3) ozarkana. These are repre- 

 sented at or near the Sabine — St. Maurice division line in the Vir- 

 ginia basin by (i) whitei, (2) uhleri and (3) darto7ii. No. i is 

 almost Corbis-Vik.e, with well developed laterals, with small cor- 

 date lunule and well-defined cardinals ; No. 2 is less inflated, 

 more finely sculptured, with weaker dentition and longer lunule ; 

 No. 3 has its dentition reduced to cardinals, while between the 

 more distant concentric raised lines, the fine radiate lines are 

 conspicuous. No. 3 quickl)^ passes into huge toothless forms in 

 the St. Maurice and dies out as the smaller subvexa in the Clai- 

 borne. Nos. I and 2 seem remarkably poorly represented in the 

 St. Maurice stage. We have a few specimens of No. i from the 

 Orangeburg District, S. C, and have seen an imperfect valve of 

 No. 2 from Texas. But in the Claiborne sand one finds such 

 specimens in abundance. The elliptical, miniature Corbis-like 

 smithi of the upper Sabine (pi. 38, figs. 2-4) becomes more ele- 

 vated, with more pronouncedly differentiated surface sculpture, 

 passing on the one hand directly from pomilia \.o the elevated, 

 wavy alveata, and on the other less directly to the smoother 

 forms with more sharply defined dorsal areas, carinifera of Con- 

 rad. All these might well be referred to one species if one cared 

 to combine all that seem to show direct relationship. No. 2 of the 

 Sabine, is perhaps represented in the Claiborne by papyracea, 

 with its comparatively smooth surface, long lunule, weak denti- 

 tion, &c. But occasionally startling resemblances occur between 

 some members of this line of descent and some members of the 

 p07nilia branch. A form from Jackson, Miss., probably the 



