NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 605 



*Plagiola elegans BAKER, Moll. Chicago, Pt. 1, 1898, p. 91, pi. xxi, fig. 1. 



Unio truncatus SAY, Am. Conch., VI, 1834.* FERUSSAC, Guer. Mag., 1835, p. 27. 



* CONRAD, Am. Conch, (continuation), Pt. 7, pi. LXVII (no date) ; * Pr. Ac. 

 N. Scl. Phila., VI, 1853, p. 259.* KUSTKR, Conch. Cab., 1861, p. 174, pi. LV, 

 figs. 2, 3. 



* Unio truncatus RAFINESQUE var. elegans. * P.ETEL, Conch. Sam., Ill, 1890, p. 170. 



Mississippi drainage generally; Michigan; Lake Michigan; south- 

 west to Trinity Eiver, Texas. 



(Group of Plagiola donaciformis.) 



Shell small, elongated, triangular oval; posterior ridge generally well 

 denned but rarely sharp, having broken green rays which form chev- 

 rons or blotches on a lighter ground; female shell somewhat inflated 

 in the post-basal region. 



t PLAGIOLA DONACIFORMIS Lea. 



* Unio donaciformis LEA, Tr. Am. Phil. Soc., Ill, 1828, p. 267, pi. iv, fig. 3 ; * Obs., I, 



1834, p. 9, pi. iv, fig. 3. * FERUSSAC, Guer. Mag., 1835, p. 27. * DESHAYES, An. 

 sans Vert. 2d ed.,VI, 1835, p. 547; 3d ed., II, 1839, p. 672. * HANLEY, Test. 

 Moll., 1842, p. 183; *Biv. Shells, 1843, p. 183, pi. xxn, fig. 41. * CATLOW and 

 REEVE, 1845, p. 58. *CHENU, 111. Conch., 1858, pl.xi, figs. 4, 4a,4&. *B. H. 

 WRIGHT, Check List, 1888. 



* Margarita ( Unio) donaciformis LEA, Syn., 1836, p. 18; 1838, p. 16. 

 *Margaron (Unio) donaciformis LEA, Syn., 1852, p. 24; 1870, p. 36. 



* Plagiola donaciformis BAKER, Moll. Chicago, Pt. 1, 1898, p. 92, pi. xm, fig. 4. 



* Unio zigzag LEA, Tr. Am. Phil. Soc., Ill, 1829, p. 440, pi. xn, fig. 19 ; * Obs., 1, 1834, 



p. 54, pi. xn, fig. 19. SHORT and EATON, Transylvania Jl., 1831, p. 79. 



* DESHAYES, An. sans Vert. 2d ed., VI, 1835, p. 551; 3d ed., II, 1839, p. 673. 

 *HANLEY, Test. Moll., 1842, p. 183; * Biv. Shells, 1843, p. 183, pi. xxn, fig. 42. 



* C ATLOW and REEVE, Conch. Nora., 1845, p. 65.* KUSTER, Conch. Cab. Unio, 

 1852, p. 42, pi. vin, fig. 3. H. and A. ADAMS, Gen. Rec. Moll., 1857, p. 495. 

 *CHENU, 111. Conch., 1858, pi. vin, figs. 8, 8a, 86; Man., 1859, II, p. 138, fig. 

 670.* SOWERBY, Conch. Icon., XVI, 1866, pi. xxxix, fig. 213.* CALKINS, Pr. 

 Ottawa Ac. Sci., 1874, p. 46. *B. H.WRIGHT, Check List, 1888. * P.ETEL, 

 Conch. Sam., Ill, 1890, p. 172. 



* Margarita (Unio) zigzag LEA, Syn., 1836, p. 18; 1838, p. 16. 

 * Margaron (Unio) zigzag LEA, Syii., 1852, p. 24; 1870, p. 36. 



* Unio nervosa CONRAD, New F. W. Shells, 1834, p. 70. 



* Unio nervosus SAY, Am. Conch., VI, 1834. * FERUSSAC, Guer. Mag., 1835, p. 27. 



*CONRAL>, Pr. Ac. N. Sci. Phila., VI, 1853, p. 253. * KUSTER, Conch. Cab. 

 Uiiio, 1861, p. 175, pi. LV, fig. 4. 



Mississippi drainage generally; Alabama liiver area; southwest to 

 the Trinity River, Texas; Michigan. Seems to be gradually replaced 

 in the southwest by P. macrodon, and there are specimens which can 

 scarcely be assigned with certainty to either species. 



t PLAGIOLA MACRODON Lea. 



* Unio macrodon LEA, Pr. Ac. N. Sci. Phila., Ill, 1859, p. 154; * Jl. Ac. N. Sci. Phila., 



VI, 1862, p. 193, pi. xxvi, fig. 262; *Obs., IX, 1863, p. 15, pl.xxvi, fig. 262. 



* ? SOWERBY, Conch. Icon., XVI, 1868, pi. LXXXVIII, fig. 437.* B. H. WRIGHT, 

 Check List, 1888. * P^TEL, Couch. Sam., Ill, 1890, p. 158. 



* Margaron ( Unio) macrodon LEA, Syn. 1870. p. 37. 



Eastern Texas, northward probably into Kansas. 



