MARYLAND GEOLOGICAL SURVEY 687 



mediate pit for the reception of the tooth in the opposite valve." Conrad, 

 1864. 



" This genus is characteristically Cretaceous and has a suborbicular 

 shell feebly concentrically sculptured, rather heavy and moderately convex, 

 without any circumscribed lunule or escutcheon, the ligament external, 

 but set in a depressed area, on each side of which the valves rise to a 

 rounded dorsal limit but without becoming keeled. The internal margins 



of the valves are smooth. The hinge formula is The first 



E. 010101 



anterior left cardinal and the anterior two right cardinals are entire, the 

 others grooved or bifid. There is no trace of any lateral tooth. The pallial 

 line is almost simple ; a slight flexuosity, as in Circe, alone represents the 

 sinus. It is obvious that the animal must have had very short siphons, if 

 any, and cannot have been closely related to Dosinia, as supposed by 

 Stoliczka/' Call, 1903. 1 



A. Adult shell not exceeding 45 mm. in altitude; valves compressed, 



squarely truncate posteriorly Cyprimeria depressa 



B. Adult shell frequently exceeding 45 mm. in altitude; valves more or 



less inflated, rounded posteriorly or obliquely truncate. 



Cyprimeria major 



CYPRIMERIA DEPRESSA Conrad 

 Plate XL, Figs. 8-10 



Dosinia depressa Conrad, 1860, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. iv, 



p. 278, pi. xlvi, fig. 6. 

 Dosinia depressa Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 13. 

 Cyprimeria depressa Conrad, 1875, Kerr's Kept. Geol. Survey of North 



Carolina, Appendix, p. 9. 



Cyprimeria depressa Gabb, 1876, Proc. Acad. Nat. Sci., Phila., p. 308. 

 Cyprimeria depressa Whitfield, 1885, Mon. U. S. Geol. Survey, vol. ix, p. 156, 



pi. xxii, figs. 11, 12. (Synonymy excluded.) 

 Cyprimeria depressa Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 16. 



Description. " Longitudinally suboval, convex-depressed, inequi- 

 lateral; dorsal margin somewhat arcuated, subangular at the posterior 

 extremity; umbo flattened; beak not prominent; disk smooth or with a 

 few distant furrows ; umbo minutely and elegantly striated concentrically ; 

 length considerably more than the height." Conrad, 1860. 



1 Trans. Wagner Free Inst. Sci., Phila., vol. iii, pt. vi, p. 1282. 



