636 PROCEEDINGS 0V THE NATIONAL MUSEUM. 



* Margarita (Anodonta) f/ibbosa LEA, Syn., 1838, p. 31. 



* Anodon gibbosa CATLOW and REEVK, Conch. Nom., 1845, ]>. t>7. 

 *Margaron (Anodonta) f/ibbosa LEA, Syn., 1852, p. 51; 1870, p. 81. 



* Anodon gibbosiis SOWERBY, .Conch. Icon., XVII, 1867, pi. ix, fig. 23. 



*\ Anodonta con-penana LEA, Pr. Am. Phil. Soc., I, 1840, p. 289. 



* Anodonta conptriana LEA, Tr. Am. Phil. Soc., VIII, 1842, p. 227, pi. xx, fig. 146; 



* Obs., Ill, 1842, p. 65, pi. xx, fig. 46.* CONRAD, Pr. Ac. N. Sci. Phila., VI, 

 1853, p. 263.* H. and A. ADAMS, Gen. Rec. Moll., II, 1X57, p. 502.* CLESSIN, 

 Conch. Cab. Ano., 1874, p. 148, pi. L, figs. 3, 4.* B. H. WRIGHT, Check List, 

 1888.* SIMPSON, Pr. U. S. Nat. Mus., XV, 1892, p. 433, pi. LXXIV, fig. 1. 



*Margaron (Anodonta) couperiana LEA, Syn., 1852, p. 51; 1870, p. 81. 



* Anodonta cooperiana P^KTEL, Conch. Sam., Ill, 1890, p. 178. 



t ANODONTA GIBBOSA var. DUNLAPIANA Lea. 



*t Anodonta dunlapiana'LK A, Pr. Am. Phil. Soc., II, 1842, p. 225; *Tr. Am. Phil. Soc., 

 VIII, 1842, p. 248, pi. xxvn, fig. 65; * Obs., Ill, 1842, p. 86, pi. xxvii, fig. 65. 



* SOWERBY, Conch. Icon., XVII, 1869, pi. xxm, fig. 87. * CLESSIN, Conch. 

 Cab. Ano., 1876, p. 220, pi. LXXIV, figs. 1, 2.* B. H. WRIGHT, Check List, 

 1888.* P.ETEL, Conch. Sam., Ill, 1890, p. 179. 



South Carolina to Florida. 



(Group of Anodonta suborbiculata.) 



Shell large, compressed, suborbicular, somewhat produced near the 

 center of the base, rounded in front and bluntly pointed behind, with a 

 slight posterior dorsal wing; beaks flattened, the sculpture consisting 

 of a few irregular ridges, which are generally broken into nodules 

 sometimes only corrugated; a well-defined but low posterior ridge sepa- 

 rates the smooth, shining area in front from a darker and rougher one 

 behind; epidermis with numerous delicate, capillary rays near the 

 beaks; muscle scars very large; nacre rather coppery and iridescent; 

 palleal line broken, often marked with radiating ridges. Animal 

 unknown. 1 



t ANODONTA SUBORBICULATA Say. 



Anodonta suborbiculata SAY, New Harm. Disseminator (newspaper form), January 

 29, 1831; Am. Conch. I, No. II, 1831. pi. XL * CONRAD, New F. W. Shells, 

 1834, p. 73. *FERUSSAC, Guer. Mag., 1835, p. 25. *HANLEY, Test. Moll., 

 1842, p. 222; Biv. Shells, 1843, p. 222. *CHENU, Bib. Conch., 1st ser., Ill, 

 1845, p. 18, pi. in, figs. 1, lo.* CONRAD, Pr. Ac. Nat. Sci. Phila., VI, 1853. 

 p. 264. * H. and A. ADAMS, Gen. Rec. Moll, II, 1857, p. 503. * CLESSIN, Conch. 

 Cab. Ano., 1874, p. 160, pi. LII, figs. 1, 2.* B. H. WRIGHT, Check List, 1888. 

 *P^ETEL, Conch. Sam., Ill, 1890, p. 185. 



^Margarita (Anodonta) suborbiculata SAY, Syn., 1836, p. 52; 1838, p. 31. 



* Anodon suborbiculata CATLOW and REEVE, Conch. Nom., 1845, p. 68. 



*Margaron (Anodonta) suborbiculata SAY, Syn., 1852, p. 51; 1870, p. 81. 



* Anodon suborbiculatus SOWKRBY, Couch. Icon., XVII, 1867, pi. v, fig. 11. 



Nebraska, Iowa; Illinois; south to Louisiana. Abundant locally. 



1 Closely related to the imbecillis group, but differing in form, beak sculpture, the 

 large muscle scars, and the palleal line. 



