MARYLAND GEOLOGICAL SURVEY 359 



Family PERIPLOMATID/E. 



Genus PERIPLOMA Schumacher. 



Periploma peralta Conrad. 

 Plate XCV, Fig. 3. 



Periploma alia Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, pp. 572, 585. 



Not Anntiiia alta C. B. Adair>s, 1852. 



Feriploma alta Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 11. 



Periploma alta Conrad, 1866, Amer. Jour. Conch., vol. ii, p. 70, pi. iv, fie. 10. 



Periploma peralta Conrad, 1867, Amer. Jour. Conch., vol. iii, p. 188. 



Periploma peralta Dall, 1903, Trans. Wagner Free Inst. Sci.,' vol. iii, pt. vi, p. 1529. 



Z>esm>^ton — " Suborbicular, subequilateral, anterior side Biibros- 

 trated, end truncated, direct ; basal margin profoundly rounded medially 

 and posteriorly; anteriorly obliquely truncated or very slightly emargi- 

 nate. 



"A much larger species than P. (Anatina) pajnjracea, Say, but closely 

 allied." Conrad, 1863. 



Shell large, depressed, thin; valves subeircular; external surface 

 minutely pustulose. 



Length, 63 mm.; height (of fragment), 55 mm. 



Occurrence. — St. Mail's Formation. Cove Point. 



Collection. — Maryland Geological Survey. 



Family THRACIID/E. 



Genus THRACIA Leach. 



Thracia conradi Couthouy. 



Plate XCV, Fig. 4. 



Thracia declivis Conrad, 1831, Amer. Mar. Conch., p. 44, pi. ix, ficr. 3; not of 

 Pennant, 1777, Brit. Zool., vol. iv, p. 15 ; nor of Donovan (fide Couthouy) 

 Conrad's synonymy excluded. 



Thracia Conradi Couthouy, 1839, Bost. Jour. Nat. Hist., vol. ii, p. 153, pi. iv, fig. 2. 



Thracia Conradi Gould, 1841, Invert Mass., p. 50. 



Thracia Conradi DeKay, 1848, Nat. Hist. N. Y., Zoology vol. i, p. 237, pi. xxviii 

 fig. 284. 



Thracia Conradi Gould (Binney's), 1870, Invert. Mass., p. 69, fig. 384. 



Thracia Conradi Dall, 1889, Bull, xxxvii, U. S. Nat. Mus., p. 64, pL Ixix, fig. 9. 



Thracia Conradi Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, pt. vi, p. 1524. 



Description. — " Shell transversely ovate, ventricose, very light, brittle 

 and thin, rather faintly diaphanous by reason of its want of thickness. 



