636 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



*Margarita {Anodonta) giibosa JjISA, Syn., 1838, p. 31. 

 *Anodon gihhosa Catlow and Reeve, Conch. Nom., 1845, p. 67. 

 *Margaron {Anodonta) gihhosa Lea, Syn., 1852, p. 51; 1870, p. 81. 

 ""Anodon gibhosus Sowerby, Conch. Icon., XVII, 1867, pi. ix, fig. 23. 

 ""] Anodonta cowperiana Lea, Pr. Am. Phil. See, I, 1840, p. 289. 



* Anodonta coaperiana 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, 1857, 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, tig. 1. 

 "Margaron (Anodonta) couperiana Lea, Syn., 1852, p. 51; 1870, p. 81. 



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



t ANODONTA GIBBOSA var. DUNLAPIANA Lea. 



''i Anodonta dimlapianal^EA, Pr. Am. Phil. Soc, II, 1842, p. 225; *Tr. Am. Phil. Soc, 

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

 *SowEKBY, Conch. Icon., XVII, 1869, pi. xxiii, fig. 87.— * Clessin, Conch. 

 Cab. Ano., 1876, p. 220, pi. lxxiv, figs. 1, 2.— *B. H. Wright, Check List, 

 * P^tel, Conch. Sam., Ill, 1890, p. 179. 



South Oaroliua 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.^ 



t ANODONTA SUBORBICULATA Say. 



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

 29, 1831 ; Am. Conch. I, No. II, 1831. pi. xi.— * Conrad, New F. W. Shells, 

 1834, p. 73.— *Ferussac, Guer. Mag., 1835, p. 25.— * PIanley, Test. Moll., 

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

 1845, p. 18, pi. Ill, figs. 1, la.—* 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.— 

 *Pjetel, 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 Sowerby, Conch. Icon., XVII, 1867, pi. v, fig. 11. 



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



' Closely related to the inibecillis group, but difiering in form, beak sculpture, the 

 large muscle scars, and the palleal line. 



