MARYLAND GEOLOGICAL SURVEY 201 



Occurrence. — Talbot Formation. Wailes Bluff near Cornfield Har- 

 bor, and Langleys Bluff, St. Mary's County. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 and U. S. National Museum. 



Superfamily VENERACEA. 

 Family PETRICOLIDAE. 



Genus PhTRICOLA Lamarck. 



Petricola pholadiformis Lamarck. 



Petricola pholadiformis Lamarck, 1818, An. S. Vert., vol. v, p. 505. 

 Petricola pholadiformis Holmes, 1858, Post-PL Fos. S. C, p. 38, pi. vii, fig. 6. 

 Petricola pholadiformis. Dall, 1889, Bull. U. S. Nat. Mus., No. 37, p. 58, pi. 



lix, fig. 15; pi. lxiv, fig. 140a. 

 Petricola (Petrlcolaria) pholadiformis Dall, 1900, Trans. Wagner Free Inst. 



Sci., vol. iii, pt. v, p. 1061. 



Description. — " P. testa transversim elongata, latere postico brevissimo, 

 sulcis longituclinalibus lamelloso-dentalis utrinque rediata; antico sub- 

 glabro." Lamarck, 1818. 



A single broken shell of this species has been found in the Maryland 

 Pleistocene. It ranges in the Pleistocene from Massachusetts to South 

 Carolina, and in the Becent from Prince Edward Island to Florida, to 

 St. Thomas in the West Indies, and to Nicaragua, and to other portions 

 of the Antillean region. 



Occurrence. — Talbot Formation. Wailes Bluff near Cornfield Hax*- 

 bor, St. Mary's County. 



Collections. — IT. S. National Museum. 



Family VENERIDAE. 

 Subfamily VENERINAE. 



Genus VENUS (Linne) Lamarck. 



Venus mercenaria Linne. 



Plates LVIII, LIX. 



Venus mercenaria Linne, 1758, Syst. Nat, ed. x, p. 686. 

 Mercenaria violacea Holmes, 1858, Post-PL Fos. S. C, p. 33, pi. vi, fig. 11. 

 Mercenaria notata Holmes, 1858, Post-PL Fos. S. C, pp. 34, 35, pi. vi, fig. 13. 

 Venus mercenaria var. notata Dall, 1903, Trans. "Wagner Free Inst. Sci., 

 vol. iii, pt. vi, pp. 1311-1315. 



