NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON, 741 



Phila., VI, 1853, p. 248. "H. and A. ADAMS, Gen. Rec. Moll., II, 1857, p. 

 493. *B. H. WRIGHT, Check List, 1888. * PJETEL, Conch. Sam., Ill, 1890, 

 p. 150. 



* Margarita ( Unio) declivis LEA, Syn., 1836, p. 32; 1838, p. 22. 



* Margaron ( Unio) declivis LEA, Syn., 1852, p. 33; 1870, p. 54. 



UNIO TETRALASMUS var. SAYI Ward. 



*Unio sayi WARD (in Tappan), Am. Jl. Sci., XXXV, 1839, p. 268, pi. in, fig. 1. 

 CONRAD, Mouog.. XI, 1838?, p. 102, pi. LV, fig. 2. 1 * KUSTER, Conch. Cab. 

 Unio, 1861, p. 246, pi. LXXXIII, fig. 1. * P.ETEL, Conch. Sam., Ill, 1890, p. 

 166. 



* Unio sayanus B. H. WRIGHT, Check List, 1888. 



* Unio eleotrinus REEVE, Conch. Icon., XVI, 1865, pi. xxv, fig. 121. *P/ETKL, 



Conch. Sam., Ill, 1890, p. 151. 



Lower Mississippi drainage north to about latitude 40 ; Ohio River 

 system; Alabama River system and southwest through Texas into 

 northern Mexico. Not reported, so far as I know, from the Tennessee 

 and Cumberland rivers. 



tUNIO COLUMBENSIS Lea.- 



*Unio columbensis LEA, Pr. Ac. N. Sci. Phila., IX, 1857, p. 31; *J1. Ac. N. Sci. 



Phila., IV, 1858, p. 75, pi. xiv, fig. 55; * Obs., VI, 1858, p. 75, pi, xiv, fig. 55. 



" B. H. WRIGHT, Check List, 1888. 

 * Margaron ( Unio) columbensis LEA, Syn., 1870, p. 50. 

 *Unio columMensis P^ETEL, Conch. Sam., Ill, 1890, p. 148. 



Chattahoochee River, Georgia, west to Little Patsaliga Creek, Ala- 

 bama. 



tUNIO OBESUS Lea. 



*? Unio carolinensis Bosc, s Hist. Nat. de Coq., 1824, III, p. 139, pi. xxm, fig. 2. 

 *FERUSSAC, Guer. Mag., 1835, p. 26. *CHENU, 111. Conch., 1843, pi. xvm, 

 fig. 4.* CONRAD, Pr. Ac. N. Sci. Phila., VI, 1853, p. 246. 



MZThio obesus LEA, Tr. Am. Phil. Soc., IV, 1831, p. 96, pi. xin, fig. 26; *Obs., I, 

 1834, p. 106, pi. xm, fig. 26. * CONRAD, N. F. W. Shells, 1834, p. 70. *HAN- 

 MBY, Test. Moll., 1842, p. 198; *Biv. Shells, 1843, p. 198, pi. xxn, fig. 34. 



* CATLOW and REEVE, Conch. Nora., 1845, p. 61. * H. and A. ADAMS, Gen. Rec. 

 Moll., II, 1857, p. 492." CHENU, 111. Conch., 185, pi. xvm, figs. 4, 4a, 4&. 



* KUSTER, Conch. Cab. Unio, 1861, p. 196, pi. LXIII, fig. 2.* REEVE, Conch. 

 Icon., XVI, 1864, pi. xvm, fig. 84. * ?SOWERBY, Conch. Icon., XVI, 1866, 

 pi. xxxvin, fig. 212. *B. H. WRIGHT, Check List, 1888. * P^TEL, Conch. 

 Sam., Ill, 1890, p. 161.* SIMPSON, Pr. U. S. Nat. Mus., XV, 1892, p. 428, pi. 

 LXVIII, fig. 6; LXIX, figs. 1, 2, 4; LXXI, fig. 3. 



* Margarita ( Unio) obesus LEA, Syn., 1836, p; 30; 1838, p. 21. 



* Margaron ( Unio) obesus LEA, Syn., 1852, p. 32; 1870, p. 50. 



1 Unio sayanus on plate, U, sayi in note. 



2 This species almost merges into obesus on the one hand and the southern forms of 

 tetralasmus on the other. The distribution of obesus is eastern, that of tetralasmus 

 western, while columbensis occupies a central position in streams of the Gulf drainage. 



3 It is impossible to tell from the very poor figure what this is. Lea thinks it is 

 Margaritana margaritifera, but Bosc did not visit any region where that species is 

 found, and the figure seems to show lateral teeth. It is quite probably U. obesus. 

 I think Lea's name had better be used. 



