500 i'i;<>ri-:i-:in\<;s or rni: NATK>X.\I. Mi'si-:r.\i. 



Bib. Conch.. 1st ser., III. 1845, p. 17, pi. in, tig. 6. * CATLOW and KRKVK, 

 Conch. Nom., 1845, p. 65. H. and A. ADAMS, Gen. Her. Moll.. II, 1K">7, p. 

 495. ]',. II. WRIGHT, Clu-ck List, 1888. I'.KTKL, Conch. Sam., III. 1890, p. 

 171. 



* Margarita ( i'nio) ribex LEA, Syu., 1836, p. 27; 1838, p. 20. 



* Margaron ( Unio) riber LEA, Syn., 1852, p. 30; 1X70, p. 48. 



t * Unio ej-igntis LKA, Pr. Am. Phil. Soc., I, 1840, p. 287.* Tr. Am. Phil. Soc., VIII, 

 1842, p. 191, pi. vn, fig. 1 ; * Obs., Ill, 1842, p. 29, pi. vn, fig. 1. " CONRAD, Pr. 

 Ac. N. Sci. l'hila.,VI, 1853, p. 248.* H. and A. ADAM*, Gen. Rec. Moll., II, 

 1857, p. 494.* CHEXU, 111., Conch., 1858, pi. xxx, figs, 1, lo, 1&. 1 * SOWKRBY, 

 Conch. Icon., XVI, 1866, p. 38, fig. 208.* H. H. WRIGHT, Check List, 188X. 

 P.KTKL, Conch. Sam., Ill, 1890, p. 152. 



* Margaron ( Unio) exigun* LEA, Syn., 1852, p. 27; 1870, p. 43. 



\*Unio staynalis CONRAD, Ann. and Mag. N. Hist.. IV, 1849, p. 300; *Pr. Ac. N. 

 Sci. Phila., IV, 1849, p. 153;- Jl. Ac. N. Sci. Phila., I, 1850, p. 275, pi. xxx vn, 

 fig. 2; Pr. Ac. N. Sci. Phila., VI, 1853, p. 257.* H.and A.ADAMS, Gen. Rec. 

 Moll., II, 1857, p. 495. *B. H. WRIGHT, Check List, 1888.* P.KTKL, Conch. 

 Sam., Ill, 1890, p. 168. 



* Margaron ( Unio) stagnalis LEA, Syn., 1852, p. 27 ; 1870, p. 12. 



t -I'nio rutilan* 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. 41. 

 * KUSTER, Conch. Cab. Unio, 1861, p. 258, pi. LXXXVII, fig. 3. * B. H. 

 WRIGHT, Check List, 1888. * P^ETEL, Conch. Sam., Ill, 1890, p. 166. 



* Margaron ( Unio) rutilans LEA, Syn., 1870, p. 45. 



\*Unio subellipsis LEA, Pr. Ac. N. Sci. Phila., VIII. 1856, p. 262; Jl. 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) siibellijms LEA, Syn., 1870, p. 45. 



* Unio prevostianus SOWERBY, Conch. Icon., XVI, 1868, pi. LXIII, fig. 315. 



* Unio subangnlatns SOWERBY, :! Conch. Icon., XVI, 1868, pi. LXV, fig. 327. 



tLAMPSILIS VIBEX var. NIGRINUS Lea.< 



* I'nio nigrinim LKA, Tr. Am. Phil. Soc., X, 1852, p. 284, pi. xxiv, fig. 44; *Obs., 



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, 

 Check List, 1888. * P.KTKL, Conch. Sam., Ill, 1890, p. 161. 



* Margaron ( Unio) nigrinus LKA, Syn., 1852, p. 39; 1870, p. 62. 



t * Unio Jioridensis S. H.WRIGHT, Conch. Exchange, II, 1888, p. 105. 

 t *Unio arerillii B. H. WRIGHT, Pr. Ac. N. Sci. Phila., XXIII, 1888, p. 115, pi. ill, 

 fig. 2. B. H. WRIGHT, Check List, 1888. 



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

 in Florida, south to the Hillsborough River. 



1 Poor figures, not all accurate. 



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

 evenly oval or elliptical form than 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 siibellipsis 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 ine to believe that the latter may perhaps be distinct. 



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



4 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 

 Chattahoochoo region. 



