560 PBOCEEDINdS OF THE NATIONAL MUSEUM. 



Bill. Concli., 1st ser., Ill, 1845, p. 17, pi. iii, fig. 6.— " Catlow and RpjEve, 



Conch. Nom., 1845, p. 65. — *H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 



495._>^ B. H. Wright, Check l.ist, 1888.— '■ P.etel, Conch. Sam., Ill, 1890, p. 



171. 

 *Mar</arUa ( Uiiio) vibex Lea, Syn., 1836, p. 27; 1838, p. 20. 

 ''Mar(jaron ( Unio) vibex Lea, Syn., 18.52, p. 30; 1870, p. 48. 

 t * Umo engmis Lea, Pr. Am. PhiL Soc, I, 1840, p. 287.—^* Tr. Am. Phil. Soc, VIII, 



1842, p. 191, pi. VII, fig. 1 ; * Obs., Ill, 1842, p. 29, pi. vii, fig. 1.—* Conrad, Pr. 



Ac. N. Scl. Phila,.,VI, 1853, p. 248.— ■ H. and A. Adams, Gen. Eec. Moll., II, 



1857, p. 494. — '' Chenu, 111., Conch., 1858, pi. xxx, figs, 1, la, 16.^ — *- Sowerby, 



Conch. Icon., XVI, 1866, p. 38, fig. 208.—* B. H. Wright, Check List, 1888.— 



•'P^ETEL, Conch. Sam., Ill, 1890, p. 1.52. 

 * Margaron (Unio) exiguus Lea, Syn., 1852, p. 27; 1870, j). 43. 

 t * Unio stagnalis Conrad, Ann. and Mag. N. Hist., IV, 1849, p. 300; * Pr. Ac. N. 



Sci. Phila., IV, 1849, p.l53;3 Jl. Ac. N. Sci. Phila., I, 1850, p. 275, pi. xxxvii, 



fig. 2; Pr. Ac. N. Sci. Phila., VI, 1853, p. 257.—" H. and A. Adams, Gen. Eec. 



Moll., II, 1857, p. 495.— *B. H. Wright, Check List, 1888.— * P.etel, Conch. 



Sam.,III, 1890,p. 168. 

 '* Margaron ( Unio) stagnalis Lea, Syn., 1852, p. 27 ; 1870, p. 42. 

 t "Unio rutilans Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 262; * Jl. Ac. N. Sci. 



Phila., IV, 1858, p. 59, pi. ix, fig. 41; * Obs., VI, 1858, p. 59, pi. ix, fig. 4L— 



^< Kuster, Conch. Cab. Unio, 1861, p. 258, pi. Lxxjivii, fig. 3.— • B. H. 



Wright, Check List, 1888.— * PvEtel, Conch. Sam., Ill, 1890, p. 166. 

 ^'Margaron ( Unio) rutilans Lea, Syn., 1870, p. 45. 

 t*Z7jiio subellipsis Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 262; *J1. Ac. N. Sci. 



Phila., IV, 1858, p. 62, pi. x, fig. 44 ; * Obs., VI, 1858, p. 62, pi. x, fig. 44.— * B. 



H. Wright, Check List, 1888. 

 "^Margaron ( Unio) sHbellipsis Lea, Syn., 1870, p. 45. 



* Unio p7-evostianus Sowerby, Conch. Icon., XVI, 1868, pi. lxiii, fig. 315. 

 ^Unio subangnlatus Sowerby,^ Conch. Icon., XVI, 1868, pi. lxv, fig. 327. 



t LAMPSILIS VIBEX van NIGRINUS Lea.* 



*Unio nigrinus Lea, Tr. Am. Phil. Soc, X, 1852, p. 284, pL xxiv, fig. 44; *0b8., 

 V, 1852, p. 40, pi. XXIV, fig. 44.— * Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 

 253.— *H. and A. Adams, Gen. Rec. Moll., II, 1857, p. 492.— *B. H.Wright, 

 . Clieck List, 1888.— -^ P^tel, Conch. Sam., Ill, 1890, p. 161. 



""Margaron ( Unio) nigrinus Lea, Syn., 1852, p. 39; 1870, p. 62. 



i *UniofloridensisS. H.Wright, Conch. Exchange, II, 1888, p. 105. 



]*Unio arerillii B. H. AVright, Pr. Ac. N. Sci. Phila., XXIII, 1888, p. 115, pi. iii, 

 fig.2.— B. H.Wright, Check List, 1888. 



Ogeechee Eiver, Georgia, west to Jackson, Mississippi; the variety 

 in Florida, south to the Hillsborough Eiver. 



' Poor figures, not all accurate. 



2 This seems to be equivalent to a male subellipsis of Lea, of a little more solid, 

 evenly oval or elliptical form thau the type. I do not think it worthy of a varietal 

 name, as there is every possible gradation between these shells. I formerly placed 

 exiguus, rutilans, and subellipsis in the synonymy of modioliformis (Proc. U. S. Nat. 

 Mus., XV, 1892, p. 414), and in a young state they seem to be exactly alike, as a gen- 

 eral thing; but the examination of a large amount of additional material since 

 then has led me to believe that the latter may perhaps be distinct. 



"' Probably a young specimen, rather wide at the posterior end. 



'* A smaller, shorter, fragile form, generally having a rather dark epidermis, and 

 purplish nacre. It is a southern variety, and gradually merges into the type in the 

 Chattahoochee region. 



