NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 749 



tPLEUROBEMA ACUENS Lea. 



* Unio ar,uens LEA, Pr. Ac. Nat. Sci. Phila., 1, 1871, p. 190; * Jl. Ac. Nat. Sci. Phila., 



VIII, 1874, p. 27, pi. VHI, fig. 24; * Obs., XIII, 1874, p. 31, pi. vm, fig. 24. 

 *B. H. WRIGHT, Check List, 1888. * PVETKL, Conch. Sam., Ill, 1890, p. 143. 



Tennessee River system. 



t PLEUROBEMA ORNATA Lea. 



* Unio ornatm LKA, Pr. Ac. N. Sci. Phila., V, 1861, p. 4; * Jl. Ac. N. Sci. Phila.. 



V, 1862, p. 85, pi. xi, fig. 234; * Obs., VIII, 1862, p. 89, pi. xi, fig. 234. 

 *P.ETKL, Conch. Sam., Ill, 1890, p. 162. 



* Margaron ( Unio) ornatus LEA, Syn., 1870, p. 57. 1 



Alabama. 



tPLEUROBEMA APPRESSA Lea. 



*Unio opjjreasHs LEA, Pr. Ac. N. Sci. Phila., I, 1871, p. 189; * Jl. Ac. N. Sci. Phila,, 

 VIII, 1874, p. 12, pi. in, fig. 8.* Obs., Ill, 1874, pi. in, fig. 8. *B. PI. 

 WRIGHT, Check List, 1888. 



* Unio argentens SOWERBY, Conch. Icon., XVI, 1866, pi. xxxvii, fig. 204. 



iUnio tuscumbiensis LEA, Pr. Ac. N. Sci. Phila., I, 1871, p. 191; * Jl. Ac. N. Sci. 

 Phila., VIII, 1874, p. 11, pi. in, fig. 7; * Obs., XIII, 1874, p. 15, pi. in, fig. 7. 

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



* Unio flavidm LEA, Pr. Ac. N. Sci. Phila., II, 1872, p. 156; * Jl. Ac. N. Sci. Phila., 



VIII, 1874, p. 28, pi. ix, fig. 25; * Obs., XIII, 1874, p. 32, pi. ix, fig. 25. 

 * B. H. W T RIGHT, Check List, 1888. 



Tennessee River system. 



tPLEUROBEMA TESSERUL^ Lea. 



* Unio tesserulce LEA, Pr. Ac. N. Sci. Phila., VI, 1861, p. 392; ' Jl. Ac. N. Sci. Phila., 



VI, 1866, p. 40, pi. xv, fig. 39 ; * Obs., XI, 1867, p. 44, pi. xiv, fig. 38.* B. H. 

 WRIGHT, Check List, 1888. 



*Margaron ( Unio)' tesseruln; LEA, Syn., 1870, p. 36. 



Nolachucky River, Tennessee. 



tPLEUROBEMA VALIDA Lea. 



*Unio validus LEA, Pr. Ac. N. Sci. Phila., I, 1871, p. 189; *J1. Ac. N. Sci. Phila., 

 VIII, 1874, p. 6, pi. I, fig. 2; *Obs., > III, 1874, p. 10, pl.i, fig. 2. * B. H. 

 WRIGHT, Check List, 1888. 



Tennessee. 



tPLEUROBEMA ABACUS Haldeman. 2 



* Unio abacus HALDEMAN, Jl. Ac. N. Sci. Phila., VIII, 1842, p. 202. * CONRAD, 



Pr. Ac. N. Sci. Phila., VI., 1853, p. 244. *H. and A. ADAMS, Gen. Rec. Moll., 



II, 1857, p. 495.* B. H. WRIGHT, Check List, 1888.* P.ETEL, Conch. Sam., 



III, 1890, p. 143. 



'Margaron (Unio) abacus LEA, Syn., 1852, p. 24; 1870, p. 38 



Tennessee and southwest Virginia. 



1 The only specimen I have seen (the type) is a young shell, which I can not refer 

 with certainty to any other species. 



2 As this species was not figured and I have not seen the type, I am nnable to be 

 absolutely certain what it is. In the Lea collection are four specimens labeled 

 " Unio abacus Hald.," which are close to appressus. 



