790 PROCEEDINGS OF TEE .Y.f 77O.Y.//. Ml'SEUM. 



t QUADRULA PLENA Lea. 



* Unio jWewuaLEA, Tr. Ain. Phil. Soc., 1, 1840, p. 286; *Tr. Am. Phil. Soc., VIII, 1843, 



p. 211, pi. xiv, fig. 26; * Obs., Ill, 1842, p. 49, pi. xiv, fig. 26.* CONRAD, Proc. 

 Ac. N. Sci. Phila.,VI, 1853, p. 255. *H. and A. ADAMS, Gen. Rcc. Moll., II, 1857, 

 p. 495. *KUSTER, Conch. Cab., 1861, p. 264, pi. LXXXIX, fig. 3. * SOWERBY, 

 Conch. Icon., XVI, 1868, pi. LXI, fig. 305. *B. H. WKIGIIT, Check List, 1888. 



* P.ETKL, Conch. Sam., Ill, 1890, p. 163. 



* Margaron ( Unio) plenus LEA, Syn., 1852, p. 25; 1870, p. 39. 



Ohio, Cumberland, and Tennessee riversystems ; southwest to Kansas 

 and Arkansas. 



QUADRULA FLEXUOSA Simpson. 



Holston Itiver, Tennessee. 



Quadrula flexuosa SIMPSON, Proc. Ac. N. Sci. Phila., 1900, p. 83, pi. n, fig. 8. 

 t QUADRULA PYRAMIDATA Lea. 



* Unio pyramidatus LEA, Tr. Am. Phil. Soc., IV, 1834, p. 109, pi. xvi, fig. 39 ; * Obs., T, 



1834, p. 119, pi. xvi, tig. 39. *HANLEY, Test. Moll., 1842, p. 186; * Biv. Shells, 

 1843, p. 186, pi. xx, fig. 45.* DESHAYES, Traite Elem. de Conch., II, 1850?, p. 

 216, pi. xxxi, figs. 1, 2. *CATLOW and REEVE, Conch. Xom., 1845, p. 63. 

 *H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p.495. 'CHENU, 111. Conch., 

 1858, pi. xvi, figs. 5, 5a. 55. * SOWERBY, Couch. Icon., XVI, 1868, pi. LXI v, p. 

 323.* B. H. WRIGHT, Check List, 1888. 



* Margarita ( Unio) pyramidatus LEA, Syn., 1836, p. 21; 1838, p. 17. 

 "Margaron ( Unio) pyramidatus LEA, Syn., 1852, p. 25; 1870, p. 39. 



* Unio mytiloides DESHAYES, Enc. Meth., II, 1830, p. 586, pi. CCXLIX, fig. 4. 



*SAY, Am. Conch., Pt. 6, 1834. *FKRUSSAC, 1835, p. 28. "MoLLKR, Syn. 

 Xov. Gen., 1836, p. 209. * CONRAD, Monog., IV, 1836, p. 41, pi. xx. 



* SWAINSON, Treatise on Mai., 1840, p. 267, figs. 52-53. * CATLOW and REEVE, 

 Conch. Nom., 1845, p. 61.* KUSTER, Conch. Cab., 1852, p. 59, pi. xin, fig. 3; 

 1861, p. 265, pi. LXXXIX, fig. 4. "B. H. WRIGHT, Check List, 1888. 



*Mar(jarltu (I'nio) mytiloides LEA, Syn., 1836, p. 21; 1838, p. 17. 

 *Margaron (Unio) mytiloides LEA, Syn., 1852, p. 25; 1870, p. 39. 



* Unio mytiloides Raiinesque var. pyramidatiu P.ETEL, Conch. Sam., Ill, 1890, p. 



160.' 

 *Unio cardiacea GUEUIN, Icon. Regne Animal, 1829?, II, pi. xxvni, lig. 7. 



* Unio ruler CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 257. 

 *Unio obliqua WOOD, Ind. Test, rev., 1856, p. 200, pi. I, fig. 8. 



Ohio, Cumberland, and Tennessee river systems; southwest to 

 Arkansas; west to Nebraska?; north in the Mississippi to Wisconsin. 



(Group of Quadrula tsubrotunda.) 



Shell solid, rounded, elliptical or ovate, with high beaks curved 

 inward and forward over a distinct lunule; beak sculpture a few coarse 



1 Most of the authors who use the name mytiloides believe it to be Rafinesque's 

 species, though they figure and describe the pyramidatus of Lea. The specimens in 

 the Lea collection which Dr. Lea calls mytiloides Rafinesque, are evidently a form of 

 his pyramidatus. Rafinesque's figure represents a shell very long and almost 

 straight on the posterior dorsal line, with astonishingly high beaks, and four dia- 

 tiuct, equally separated rays on the disk, and he says there are some oblique, black, 

 longitudinal bands on the shell. The Rafinesquian shell seems as near to the Unio 

 clava of Lamarck as anything, but it does not agree with that. 



