600 PROCEEDINGS OF THE NATIONAL MUSEUM. 



tOBOVARIA CIRCULUS Lea. 



* Unio circulus LEA, Tr. Am. Phil. Soc., 111,1829, p. 433, pi. ix, fig. 14 j 1 *Obs., I, 



1834, p. 47, pi. ix, fig. 14. SHORT and EATON, Transylvania Jl., 1831, p. 77. 

 *DESHAYES, An. sans Vert., 2d ed.,VI, 1835, p. 549; 3d ed., II, 1839, p. 672. 



* ANTON, Verz. der Couch., 1839, p. 14.* HANLEY, Test. Moll., 1842, p. 201; 



* Biv. Shells, 1843, p. 201, pi. xx, fig. 23.* CATLOW and REEVE, Conch. Nora., 

 1845, p. 57.* KUSTER, Conch. Cab. Unio, 1852, p. 41, pi. vm, fig. 2.* CHENU, 

 111. Conch., 1858, pi. xvi, figs. 1, la, II. *H. and A. ADAMS, Gen. Rec. Moll., 

 II, 1857, p. 492.* REEVE, Conch. Icon., XVI, 1865, pi. xxvn, fig. 135.* B. H. 

 WRIGHT, Check List, 1888. 



* Margarita ( 771(0) circulus LEA, Syn., 1836, p. 33; 1838, p. 22. 

 *Margaron ( Unio) circulus LEA, Syn., 1852, p. 34; 1870, p. 55. 



* Unio subrotundus FERUSSAC, part, Guer. Mag., 1835, p. 28. 2 CONRAD, Pr. Ac. N. 



Sci. Phila., VI, 1853, p. 258. 



* Unio subrotundus Raf. v. circulus P^ETEL, Conch. Sam., Ill, 1890, p. 168. 

 *Mya rotunda WOOD, Index Test. (Rev.), 1856, p. 199, pi. i, Supp., fig. 1. 



Ohio, Tennessee and Cumberland river systems; southeast Louisiana; 

 Alabama and Tombigbee drainage? Reported from Michigan and the 

 St. Lawrence drainage, but the forms in this area are probably 0. leibii, 

 which is perhaps only a variety of 0. circulus. 



fOBOVARIA TINKERI B.H.Wright. 



* Unio tinkeri B. H. WRIGHT, Nautilus, XIII, 1899, p. 7. 



*0lovaria tinkeri SIMPSON, Pr. Acad. Nat. Sci. Phila., 1900, p. 78, pi. iv, fig. 3. 



Tombigbee River, Alabama; Columbus, Mississippi. 



t OBOVARIA LENS Lea. 3 



* Unio lens LEA, Tr. Am. Phil. Soc. Phila., IV, 1831, p. 80, pi. vm, fig. 10; * Obs. I, 



1834, p. 90, pi. vm, fig. 10. *FERUSSAC, Guer. Mag., 1835, p. 26. * HANLEY, 

 Test. Moll., 1842, p. 201; * Biv. Shells, 1843, p. 201, pi. xxi, fig. 4.* CATLOW 

 and REEVE, Conch. Norn., 1845, p. 60. * CHENU, 111. Conch., 1856, pi. vm, 

 figs. 10, 10a, 10&. * H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p. 492. 



* REEVE, Conch. Icon., XVI, 1865, pi. xxvn, fig. 134. *SOWERBY, Conch., 

 Icon., XVI, 1866, pi. xxxvn, fig. 200.* B. H. WRIGHT, Check List, 1888. 



* P.ETEL, Conch. Sam., Ill, 1890, p. 157. 



* Margarita ( Unio) lens LEA, Syn., 1836, p. 33; 1838, p. 22. 

 *Margaron ( Unio) lens LEA, Syn., 1852, p, 34; 1870, p. 55. 



*1Unio lamgatus SAY, Am. Conch., VI, 1834. CONRAD, New F. W. Shells, 1834, p. 

 70. CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 251. 



1 The figured type has a purple nacre. 



2 Ferussac makes this= U. orbiculalus Hildreth also. 



" This is sometimes considered a synonym of 0. circulus. The two species are exces- 

 sively variable in form, and both often have a pink or purplish nacre. While indi- 

 viduals may occasionally be found which can only be referred to either species with 

 doubt, the majority of specimens can readily be determined, and Dr. V. Sterki 

 informs me that he has found differences in the animals of the two. As I have only 

 been able to examine the soft parts of young specimens I have not detected any 

 differential characters in them. 



