832 mOCEEDINGS OF THE NATIONAL MUSEUM. VOL.XXII. 



Genus DALLIELLA Simpson 19OO. 

 (Type Anodonta purpurea Valenciennes. 1 ) 



Shell subtrapezoidal, generally thin, inflated, with a low, rounded 

 posterior ridge and rather full beaks which have somewhat zigzagged 

 radial sculpture, with a row of chevron -shaped folds running some dis- 

 tance down the posterior riJge, and with line corrugations in front of 

 the beaks; epidermis somewhat cloth-like; substance of the shell of a 

 peculiar purplish -brown tint; hinge line narrow; teeth imperfectl 

 developed, sometimes reduced to mere rudiments, when present con- 

 sisting of greatly compressed, feeble, pseudocardiuals and laterals; 

 beak cavities rather shallow; dorsal scars one to a few, scattered; 

 muscle scars faint; prismatic border wide. 



Animal unknown. 



(Group of Dalliella purpurea.} 



Shell not biangulate behind, rather smooth; nacre coppery purple; 

 teeth A r ery faint, compressed. 



t DALLIELLA PURPUREA Valenciennes. 



"Anodonta purpurea VALENCIENXES, Rec. Obs. Zool., IT, 1833, p. 236, pi. XLVIII 

 bis, figs. 3, 3a, 3b. * HANLEY, Test. Moll., 1842, p. 218. * H. and A. ADAMS, 

 Gen. Rec. Moll., II, 1857, p. 503.* vox MARTENS, Mai Bl., XIV, 1866, p. 12.^ 



* CLESSIN, Conch. Cab. Ano., 1876, p. 77, pi. xix, fig. 1. * P.ETEL, Conch. 

 Sam., Ill, 1890, p. 183. 



* Margarita (Anodonta) purpurea LEA, Syn., 1836, p. 51 ; 1838, p. 30. 

 * Anodon purpurea CATLOW and REEVE, Couch. Norn., 1845, p. 67. 

 *Margaron (Anodonta) purpurea LEA, Syn., 1852, p. 50; 1870, p. 79. 



* t Anodonta bttrrougltiana, LEA, Tr. Am. Phil. Soc., V, 1834, p. 105, pi. xvi, fig. 49; 



* Obs., 1, 1834, p. 217, pi. xvi, fig. 49." CLESSIN, Conch. Cab. AUG., 1875, p. 164, 

 pi. LIV, figs. 3, 4.* P^TEL, Conch. Sam., Ill, 1890, p. 177. 



* Margaron (Anodonta) bitrroughana, LEA, Syn., 1870, p. 81. 



* Anodon burroughianus, SOWERBY, Conch. Icon., XVII, 1870, pi. xxvn, fig. 103. 



* t Margarita ( Unio) bengalensis LEA, Syn., 1836, p. 26; 1838, p. 20. 



* Unio bengalensis LEA, Tr. Am. Phil. Soc., VI, 1838, p. 3, pi. n, fig. 3; * Obs., II, 



1838, p. 3, pi. n, fig. 3.* TROSCHEL, Arch, fiir Nat., V, 1839, pi. n, p. 233. 



* HANLEY, Test. Moll., 1842, p. 194; * Biv. Shells, 1843, p. 194, pi. xxi, fig. 

 50. * CATLOW and REEVE, Conch. Nom., 1845, p. 56. * H. and A. ADAMS, 

 Gen. Rec. Moll., II, 1857, p. 493.* CHENU, 111. Conch., 1858, pi. xxn, figs. 2, 2a, 

 2b. * KUSTER, Conch. Cab. Unio, 1861, p. 228, pi. LXXVII, figs. 2, 3.* P.ETEL, 

 Conch. Sam., Ill, 1890, p. 146. 



* Margaron (Unio) bengalensis LEA, Syii., 1852, p. 30; 1870, p. 47. 



* Anodon bengalensis SOWERBY, Conch. Icon., XVII, 1867, pi. xiv, fig. 49. 



* Anodonta benyalensis CLESSIN, Conch. Cab. Ano., 1876, p. 173, pi. LVII, fig. 1. 



*PJETEL, Conch. Sam., Ill, 1890, p. 177. 



M Unio rerecundus GOULD, Pr. Boat. S. N. Hist., Ill, 1850, p. 295; * U. S. Expl. 

 Exp., XII, 1852, p. 431, figs. 541, 541a, 5416, 541c ; * Otia Couch., 1862, p. 89. 



'Some of the species placed here have been classed with Anodonta, but almost any 

 large series of specimens of any species will show variation from edentulous to 

 toothed forms. 



