44 PROCEEDINGS OF THE ACADEMY OF [Feb., 



absence of a sutural channel and of any radial sculpture other 

 than the incrementals. L. shacklefordensis is higher relatively 

 and differs in the details of the body sculpture. 



The shell is well protected by an outer percellanous covering, 

 which, in the best preserved individuals, completely conceals 

 the nacre within. The weathered shells are so highly iridescent, 

 however, that they are much more suggestive of Solariella than 

 of Liotia. 



Distribution. — Duplin Formation. Muldrow's Place, 5 miles 

 southeast of Mayesville, Sumter County, South Carolina. Not 

 uncommon. 



Collections. — U. S. National Museum. Johns Hopkins Uni- 

 versity. Academy of Natural Sciences of Philadelphia. 

 Pandora (Clidiophora) prodromes new species. Plate IV, flgs. 9, 11, 12, 14. 



General Characters. — Shell of moderate dimensions, rather heavy, 

 compressed. Inequivalve. Strongly inequilateral. Sub-quadrate 

 in outline. Umbones very low and inconspicuous, often perforate, 

 strongly anterior. Lunula not developed. Escutcheon persisting 

 to the extremity of the posterior dorsal margin, sub-linear, sharply 

 delimited. Anterior extremity broadly rounded. Posterior ex- 

 tremity quite squarely truncate. Dorsal margin feebly convex. 

 Ventral margin broadly arcuate. Submarginal carina outlined 

 in the right valve by a linear sulcus, in the left by a sub-acute 

 ridge. Anterior area very obscurely differentiated, occupying 

 approximately one-third of the entire valve. 



Sculpture. — Radial sculpture not developed. Incremental sculp- 

 ture somewhat undulatory on the early portion of the valve, 

 laminar and crowded toward the ventral margin. 



Ligament. — Ligament internal, lodged, in the right valve be- 

 tween the middle and posterior cardinals and, in the left valve, 

 in a bilobed pit posteriorly produced along the dorsal margin. 



Dentition. — Hinge dentition robust. Anterior cardinal of right 

 valve almost entirely obsolete. Middle cardinal elongate, rhom- 

 bic, strongly and abruptly elevated. Posterior cardinal com- 

 pressed, elongate-cuneate, wedging out dorsally. Anterior cardinal 

 of left valve extending from the apex of the umbones to the anterior 

 adductor scar, uniformly elevated, widening slightly toward the 

 umbones. Posterior cardinal linear, inconspicuous, outlining the 

 anterior margin of the resilial pit. 



Muscle Impressions and Pallial Line. — Adductor impressions 

 small, slightly sunken, irregularly rotund, placed well up toward 



