NO. 2116. ANATINACEA FROM WEST COAST OF AMERICA— BALL. 447 



The following species of Thracia have been described from the 

 Tertiary of the Pacific coast: 



THRACIA TRAPEZOroES Conrad, 1849. 



Tertiary of Astoria, Oregon. 



THRACIA MACTROPSIS Conrad, 1857. 



Tertiary, Monterey County, California. 



THRACIA DILLERI Dall, 1898. 



Mid-Eocene, Arago beds, Oregon. 



THRACIA SEMIPLANATA Whiteaves. 



Eocene, Ventura County, California, according to Arnold. 



THRACLA. KARQUINEZENSIS Weaver, 1905. 



Eocene, Contra Costa County, Cahfornia. 



THRACIA CONDONI Dall, 1909. 



Miocene, near Eugene, Oregon. 



THRACIA JACALITOSANA Arnold, 1909. 



Miocene, Fresno County, California. 



THRACIA VENTRICOSA Conrad, 



Is a nude unidentifiable name, in Meek's Miocene Check-list, 1864. 

 There are species of Cyathodonta in the OUgocene marls of Panama, 

 but these fossils have not yet been worked up. 



Family PERIPLOMATIDAE. 

 Genus PERIPLOMA Sehumacher. 



Periploma Schumacher, Essai d'un Nouv. Syst. Vers Test., pp. 40, 115, 1817. 



Type. — P. inacquivahis Schumacher. 

 Osteodesma A, Blainville, Man., vol. 2, p. 659, 1827. 



PERIPLOMA PLANIUSCULA Sowerby. 



Periploma planiuscula Sowerby, Proc. Zool. Soc. Lond. for 1834, p. 87. Isla de 



Muerte, Guayaquil. 

 Periploma lenticularis Sowerby, Proc. Zool. Soc. Lond. for 1834, p. 87. Isla de 



Muerte, Guayaquil. 

 Periploma argentaria Conrad, Journ. Acad. Nat. Sci. Phila., vol. 7, p. 238, pi. 18, 



fig. 8, 1837. California. 

 Periploma ohtusa Hanley, 111. Lamarck's Shells, pi. 2, fig. 50, 1842. " West 



America." 

 Periploma alta C. B. Adams, Panama Shells, p. 292, 1852. 

 IPeriploma papyracea Carpenter, Proc. Zool. Soc. Lond. for 1855, p. 229. Mazat- 



lan; not of Say, 1822. 

 Periploma excurva Carpenter, Proc. Zool. Soc. Lond. for 1855, p. 229; Mazatlan. 

 Periploma excurvata Carpenter, Rep. Brit. Assoc. 1856, p. 287. (Error for 

 excurva.) 



Distribution. — San Pedro, California, and south to Panama and 

 Guayaquil. Cat. No. 153307, U.S.N.M. 



