790 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



tQUADRULA PLENA Lea. 



* Unio plenusl.\s.A, Tr. Am. 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. Reo. Moll., II, 1857, 

 p. 495. — * KusTER, Couch. Cab., 1861, p. 264, pi. lxxxix, fig. 3. — *Sowerby, 

 Conch. Icon., XVI, 1868, pi. lxi, fig. 305.—* B. H. Weight, Check List, 1888.— 

 * Pjetel, Conch. Sam., Ill, 1890, p. 163. 



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



Ohio, Cumberland, and Tennessee river systems; southwest to Kansas 

 aud Arkansas. 



QUADRULA FLEXUOSA Simpson. 



Holston Elver, Tennessee. 



Quadrula flexuosa Simpson, Proc. Ac. N. Sci. Phila., 1900, p. 83, pi. ii, fig. 8. 

 tQUADRULA PYRAMIDATA Lea. 



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

 1834, p. 119, pi. XVI, fig. 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 Eeeve, Conch. Nom., 1845, p. 63. — 

 *H. and A. Adams, Gen. Rec. Moll., II, 1857, p. 495. — "Chenu, III. Conch., 

 1858, pi. XVI, figs. 5, 5a, 5&.— ^Sowekby, Couch. Icon., XVI, 1868, pi. lxiv, 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.— "Ferussac, 1835, p. 28.— *M(Jller, Syn. 

 Nov. Gen., 1836, p. 209. - '^ Conrad, Monog., IV, 1836, p. 41, pL xx.— 

 *■ Sv^^AiNSON, Treatise on Mai., 1840, p. 267, figs. 52-53.— ' Catlow and Reeve, 

 Conch. Nom., 1845, p. 61.—" Kuster, Conch. Cab., 1852, p. 59, pi. xiii, fig. 3; 

 1861, p. 265, pi. Lxxxix, fig. 4.— *B. H. Wright, Check List, 1888. 



^Margarita {Unio) mytiloides Lea, Syu., 1836, p. 21; 1838, p. 17. . 



'^Margaron { Unio) mytiloides Lea, Syn., 1852, p. 25; 1870, p. 39. 



'^Unio mytiloides Rafiuesque var. iryramidatuii P.etel, Conch. Sam., Ill, 1890, p. 

 160.' 



^Unio cardiacea Guerin, Icon. Regne Animal, 1829?, If, pi. xxviii, fig. 7. 



" Unio ruber Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 257. 



*Z7nio ohliqua Wood, Ind. Test, rev., 1856, p. 200, pi. i, fig. 8. 



Ohio, Cumberland, and Tennessee river systems; southwest to 

 Arkansas; west to jSTebraska"?; north In the Mississippi to Wisconsin. 



(Group of Quadrula subrotunda.) 



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

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



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

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

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

 his pyramidatas. Rafines(iue's figure represents a shell very long and almost 

 straight on the posterior dorsal line, Avith astonishingly high beaks, aud four dis- 

 tinct, e(iually soi^arated rays on the disk, aud he says there are some oblique, black, 

 longitudiual bands on the shell. The Raflnesquiau shell seems as near to the Unio 

 clava of Lamarck as anything, but it does uot agree with that. 



