762 FBOCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



tPLEUROBEMA PYRIFORMIS Lea. 



*Unio pyriformis Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 31; * Jl. Ac. N. Sci. 



Pliila., IV, 1858, p. 69, pi. xii, fig. 50 ; * Obs., VI, 1858, p. 69, pi. xii, fig. 50.— 



* B. H. Wright, Check List, 1888. 

 *Margaron ( Unio) pyriformis Lea, Syn., 1870, p. 40. 



Near Columbus, Georgia. 



fPLEUROBEMA MODICA Lea. 



*Unio mo(?icMS Lea, Pr. Acad. N. Sci. Phila., IX, 1857, p. 171; *JL Acad. N. Sci. 



Phila., IV, 1859, p. 204, pi. xxiv, fig. 86; *Obs., VII, 1860, p. 22, pi. xxiv, 



fig. 86.—* B. H. Wright, Check last, 1888. 

 *Margaron ( Unio) modicus Lea, Syn., 1870, p. 40. 



Chattalioocliee Eiver, Georgia. 



t PLEUROBEMA STRIATA Lea. 



*Unio striatus Lea, Pr. Am. Phil. Soc, I, 1840, p. 287; * Tr. Am. Phil. Soc, VIII, 

 1843, p. 203, pi. XII, fig. 16 ; * Obs., Ill, 1842, p. 41, pi. xii, fig. 16.—* Conrad, 

 Pr. Acad. N. Sci. Phila., VI, 1853, p. 2,58.—* H. and A. Adams, Gen. Rec. Moll., 

 II, 1857, p. 496.— * Chenu, 111. Conch., 1858, pi. xxix, figs. 1, la, 1&.— *B. H. 

 Wright, Check List, 1888. 



"'Margaron {Unio) striatus Lea, Syn., 1852, p. 26; 1870, p. 40. 



Chattahoochee Eiver, Georgia. 



tPLEUROBEMA GIBBER Lea, 



* Unio giiher Lea, Tr. Am. Phil. Soc, VI, 1838, pT34, pi. x, fig. 30; * Obs., II, 1838, p. 



35, pi. X, fig. 30.— * Troschel, Arch, fur Naturg., V, 1839, Pt. 2, p. 236.— 

 *HANLEy, Test. Moll., 1842, p. 185 ; * Biv. Shells, 1843, p. 185, pi. xxi, fig. 46.— 

 *Catlow and Eeeve, Conch. Nom., 1845, p. 59.^* Conrad, Pr. Acad. N. Sci. 

 Phila., VI, 1853, p. 250.—* H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 495.— 

 *Chenu, 111. Conch., 1858, pi. xxiii, figs. 2, 2a, 2b. — * Sowerby, Conch. Icon., 

 XVI, 1866, pi. XL, fig. 219.—* B. H. Wright, Check List, 1888. 



* Margarita ( Unio) giUer Lea, Syn., 1836, p. 20; 1838, p. 17. 

 "Margaron ( Unio) gibber Lea, Syn., 1852, p. 24 ; 1870, p. 37. 



Caney Fork, Tennessee. 



tPLEUROBEMA FASSINANS Lea. 



* Uniofassinans Lea, Pr. Ac. N. Sci. Phila., XII, 1868, p. 143 ; * Jl. Ac. N. Sci. Phila., 



VI, 1869, p. 305, pi. XLVii, fig. 118; *Obs., XII, p. 65, pi. XLVii, fig. 118.— * B. 

 H. Wright, Check List, 1888. 

 *Margaron ( Unio) fassinans Lea, Syn., 1870, p. 42. 



tPLEUROBEMA FASSINANS var. RHOMBOIDEA Simpson.^ 



Upper Tennessee River drainage. 



1 A form of what I consider fassinans is abundant in the Clinch Eiver, in western 

 Virginia, which is considerably more rhomboid than the type and may be called var. 

 rhomboidea. 



