704 PROCEEDINGS OF THE NATIONAL MUSEUM. 



* Unto dilalatus Say,' Am. Conch., VI, 1834.— * Conrad, New F. W. Shells, 1834, 



p. 68.—* Ferussac, Guer. Mag., 1835, p. 27. — " Conrad, Moiiog., V, 1836, p. 

 42, pi. XXI.— "KuSTER, Conch. Cab.Unio, 1852, p. 38, pi. vi, fig. 4. — * Conrad, 

 Pr. Ac. N. Sci. Phila., VI, 1853, p. 248. 



* Unio toruloses Ferussac, Guer. Mag., 1835, p. 28. 



* Unio arctatus Ferussac, Guer. Mag., 1835, p. 29. 



n Unio arctior Lea, Tr. Am. Phil. Soc , VI, 1838, p. 10, pi. iv, fig. 10; 2 Obs., II, 

 1838, p. 10, pi. IV, fig. 10.— *Troschel, Arch, fiir Naturg., V, 1839, Pt. 2, p. 

 284.—* Hanley, Test. Moll., 1842, p. 208; ' Biv. Shells, 1843, p. 208, pi. xxii, 

 fig. 46. — * Catlow imcl Reeve, Conch. Nom., 1845, p. ,56. — * Conrad, Pr. Ac. 

 N. Sci. Phila., VI, 1853, p. 245.—^ Kuster, Conch. Cab. Uuio, 1861, p. 179, 

 pi. LVi, tig. 6. — "" H. and A. Adams, Gen. Rec. Moll., II, 1857, p. 491. — * Chenu, 

 111. Conch., 1858, pi. xxi, figs. 2, 2«,, 2&.— *? Sowerby, Conch. Icon., XVI, 1868, 

 pi. Lxxxv, fig. 2.—* B. H. Wright, Check List, 1888.—* P^tel, Conch. Sam., 

 Ill, 1890, p. 144. 



* Margarita (Unio) arctior Lea Syn., 1836, p. 39; 1838, p. 25. 

 *Margaron ( Unio) arctior Lea, Syn., 1852, p. 38; 1870, p. 71. 



fUNIO GIBBOSUS var. ARCUS Conrad. 



* Unio arciis Conrad, Am. Jl. Sci., XXV, 1834, p. 340, pi. l, fig. 8 ; *NewF. W. Shells, 



1834, p. 67.—* Ferussac, Guer. Mag., 1835, p. 29.—* Moller, Syn. Nov. Gen., 

 1836, p. 1898.— * Hanley, Test. Moll., 1842, p. 207; *Biv. Shells, 1843, p. 207, 

 pi. xxiii, fig. 46. — * Catlow and Reeve, Conch. Nom., 1845, p. 56. — * Conrad, 

 Pr. Ac.N. Sci. Phila., VI, 1853, p. 245.— 'H. and A. Adams, Gen. Rec. Moll., II, 



1857, p. 491.—* B. H. Wrigpit, Check List, 1888.—* P^tel, Conch. Sam., Ill, 

 1890, p. 144. 



* Margarita ( Unio) arciis Lea, Syn., 1836, p. 38; 1838, p. 25. 

 *Margaron ( Unio) arcns Lea, Syn., 1852, p. 38; 1870, p. 61. 



tUNIO GIBBOSUS var. SUBGIBBOSUS Lea. 



*Unio subgibbosus Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 169; Jl. Ac. N. Sci- 

 Phila., IV, 1858, p. .53, pi. vi, fig. 36; Obs., VI, 1858, p. 53, pi. VL fig. 36.— 

 * B. H. Wright, Check List, 1888.—* Simpson, Pr. U. S. Nat. Mus., XV, 1892^ 

 p. 432, pi. Lxxviii, fig. 5. 



*Margaroii (Unio) subgibbosus Lea, Syn., 1870, p. 61. 



* Unio lazarus Sowerby, Conch. Icon., XVI, 1868, pi. lxviii, fig. 348. 



* t Unio rufus Lea, Pr. Ac. N. Sci. Phila., IX, 18.57, p. 171 ; Jl. Ac. N. Sci. Phila., IV, 



1858, p. 85, pi. XVII, fig. 65; Obs., VI, 1858, p. 85, pi. xvii, fig. 65.—* B. H. 

 Wright, Check List, 1888. 



* Margaron ( Unio) rufus Lka, Syn., 1870, p. 61. 



tUNIO GIBBOSUS var. ARMATHWAITENSIS B. H. Wright. 

 *Unio gibbosus var. armathwaitensis B. H. Wright, Naut., XI, 1898, p. 123.-' 

 tUNIO GIBBOSUS var. DELICATUS Simpson. ^ 



Entire Mississippi drainage; St. Lawrence and its tributaries; Ala- 

 bama Eiver system; southeast into Florida; southwest to the Guada- 

 lupe Eiver, Texas. 



'As of Rafinesque. I am unable to make out Rafinesque's species. 



^Merely a form with white nacre. 



^ These three are dwarf varieties of gibbosus. All are often more or less humped, 

 and there are many intermediate and connecting specimens. 



'A greatly compressed, thin variety, with an evenly elliptical outline and very 

 dark nacre may bear this name. 



