69 St. Mauricr and Claiborne Pelecypoda 69 



medially, gradually rounding to the anterior margin but much 

 more suddenly depressed posteriorly where the shell is no more 

 inflated than the majority of members of this genus ; with fine 

 even striation on the lower third of the shell surface, though in 

 general above, appearing smooth ; umbonal ridge rather sharply 

 defined, with but slight traces of concentric markings ; on the 

 flat, radial space between the umbonal ridge and the margin of 

 the escutcheon the counterpart of concentric striation appears in 

 the form of even, sharpl)^ defined, very oblique lining, the mod- 

 erate, slighth' raised escutcheon shows this lining but imperfect- 

 ly ; lunule nearly as long, but narrower than the escutcheon, set 

 off from the general shell surface by a narrow, shallow channel 

 showing even, oblique growth-lines as on the post-umbonal slope 

 before described ; posterior and anterior rows of teeth strong, 

 about equal. 



In rare instance there are two or three radiating raj'S extend- 

 ing from beak to post-basal margin, suggesting those of L. hous- 

 tojiia. This shell would seem to be L. calcarensis Conrad, but 

 from the description and figure given of that species we are at a 

 loss to know whether the ventricose condition is limited to the 

 medial portion of the shell, as in our species, whether the concen- 

 tric lines cover the whole surface or not, whether the "pointed" 

 rostrum is as blunt as figured and whether the dimensions as 

 given in the description are of an adult form or not. Several of 

 our specimens from Ozark are an inch in length, Conrad gives 

 7-16 as the length of his specimen. 



It is quite probably a descendant of viilamensis. 



Types. — Paleont. Mus. Cornell Univ. 



Horizon. — St. Maurice ^Eocene. 



Specimens fig2ired . — Paleont. Mus. Cornell Univ. 



Localities. — Hamilton Bluff, Ala. (verj- abundant); Ozark, 

 Ala. (large, fine casts). 



Leda wautubbeana, n. sp., PI. 25. Fig. 15,3. 



Specific characterization. — Size and form as indicated by the 

 figure and explanation ; shell thin, flat, practically smooth med- 

 ially ; anterior with a sharply defined radiating furrow ; poster- 



