756 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



tPLEUROBEMA TROSCHELIANA Lea. 



* Unio troschelianvs Lka, Tr. Am. Phil. Soc, X, 1852, p. 280, pi. xxiii, fig. 39; * Obs., 



V, 1852, p. 36, pi. XXIII, fig. 39.— *H. and A. Adams, Gen. Rec. Moll., II, 

 1857, p. 496.— '' B. 11. Wright, Check List, 1888.— * P^tel, Conch. Sam., 

 Ill, 1890, p. 170. 

 *Margaron (Unio) troschelianus Lea, Syn., 1852, p. 26; 1870, p. 40. 



Alabama Eiver system. 



PLEUROBEMA IRRASA Lea. 



*Unio irrasus Lea, Pr. Ac. N. Sci. Phila,, V, 1861, p. 38; " Jl. Ac. N. Sci. Phila., 

 V,1862, p. 91, pi. XIII, fig. 239; *Ohs., VIII, 1862, p. 95, pL xiii, fig. 239.— 



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

 *Margaron ( Unio) irrasus Lea, Syn., 1870, p. 38. 



Coosa Eiver system. 



t PLEUROBEMA ALTA Conrad. 



* Unio alius Conrad, Jl. Ac. N. Sci. Phila., II, 1854, p. 298, pi. xxvii, fig. 5. — 



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



* Margaron {Unio) alius Lea, Syn., 1870, p. 42. 



t * Unio fibuloides Lea, Pr. Ac. N. Sci. Phila., Ill, 1859, p. 154; Jl. Ac. N. Sci. 

 Phila., IV, 1859, p. 219, pi. xxviii, fig. 100; *0b8., VII, 1859, p. 37, pL 

 xxviii, fig. 100.—* SowERBY, Conch. Icon., XVI, 1866, pi. xli, fig. 223.— 

 *B. H. Wright, Check List, 1888.— "^PiETEL, Couch. Sam., Ill, 1890, p. 152. 



Margaron (Unio) fibuloides Lea, Syn., 1870, p. 56. 



Oonuasauga River, Georgia. 



t PLEUROBEMA HARTMANIANA Lea. 



*Unio harimanianus Lea, Pr. Ac. N. Sci. Phila., IV, 1860, p. 307; *JI. Ac. N. Sci. 



Phila., V, 1862, p. 73, pi. viii, fig. 222; *Ohs., VIII, 1862, p. 77, pi. viii, 



fig. 222.— *B. II. Wright, Check List, 1888. 

 ^Margaron (Unio) harimanianus Lea, Syn., 1870, p. 38. 



Coosa Hiver, Alabama. 



Dr. Lea lias shells in his collection from the Clinch Eiver which he 

 places with this species, which I am certain belong to the Clava group. 



t PLEUROBEMA INSTRUCTA Lea. 



■ Unio instructua Lea, Pr. Ac. N. Sci. Phila., V, 1861, p. 59; *J1. Ac. N. Sci. Phila., 

 V, 1862, p. 82, pi. X, fig. 230; *Obs., VIII, 1862, p. 86, pi. x, fig. 230.— * B. H. 

 Wright, Check List, 1888. 



* Margaron ( Unio) insiructus Lea, Syn., 1870, p. 38. 



Cahawba Eiver, Alabama. 



(Group of Pleurohema shoivalterii.) 



Shell small, rounded triangular, inflated, slightly truncated ante- 

 riorly, x)Osterior end arched and ending in a bluntly rounded point at 

 the poi-t base, posterior ridge well defined; ninbonal region full; beiiks 

 ratlicr prominent, the sculpture not observed; epidermis brown, not 

 rayed; hinge plate rather wide; pseudocardinals small, triangular, 



