NO. 1205. SYNOPSIS OF THE NAIADES— SIMPSON. 741 



Phila., VI, 1853, p. 248.— ^H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 

 493.— 'B. H, Wright, Check List, 1888.— * Pjstel, Conch. Sara., Ill, 1890, 

 p. 150. 



* Margarita {Unto) declivis Lea, Syn., 1836, p. 32; 1838, p. 22. 



* Margaron (Ufiio) 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. iii, fio-. 1.— 



* Conrad, Monog., XI, 1838?, p. 102, pi. lv, fig. 2.'—* Kustkr, Conch. Cab. 

 Unio, 1861, p. 246, pi. lxxxiii, fig. 1.—" P^tel, Conch. Sam., Ill, 18!10, p. 

 166. 



* Unio say anus B. H. Wright, Check List, 1888. 



* Unio electrinus Reeve, Conch. Icon., XVI, 1865, jil. xxv, fig. 121. — * Ptetel, 



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



Lower Mississippi drainage north to about latitude 40° ; Ohio Eiver 

 system; Alabama River system and southwest through Texas into 

 northern Mexico. l!^ot reported, so far as I know, from the Tennessee 

 and Cumberland rivers. 



tUNIO COLUMBENSIS Lea.^ 



*Unio columhensis 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) columhensis Lea, Syn., 1870, p. 50. 

 *Unio columhiensis Pjstel, Conch. Sam., Ill, 1890, p. 148. 



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

 bama. 



tUNIO OBESUS Lea. 



""fUnio carolinensis Bosc,'' Hist. Nat. de Coq., 1824, III, p. 139, pi. xxiii, fig. 2.— 

 *Ferussac, Guer. Mag., 1835, p. 26 — *Chenu, 111. Conch., 1843, pi. xviii, 

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



'\Unio obesus Le.4, Tr. Am. Phil. Soc, IV, 1831, p. 96, pi. xm, fig. 26; * Obs., I, 

 1834, p. 106, pi. XIII, fig. 26.—* Conrad, N. F. W. Shells, 1834, p. 70.—* Han- 

 ley, Test. Moll., 1842, p. 198; *Biv. Shells, 1843, p. 198, pi. xxii, fig. 34.— 



* Catlow and Eeeve, Conch. Nora., 1845, p. 61. — * H. and A. Adams, Gen. Rec. 

 Moll., II, 1857, p. 492.—* Chenu, 111. Conch., 185^, pi. xviii, figs. 4, ia, 46.— 



* KusTER, Conch. Cab. Unio, 1861, p. 196, pi. LXiir, fig. 2. — * Reeve, Conch. 

 Icon., XVI, 1864, pi. xviii, fig. 84.— * ?Sowerby, Conch. Icon., XVI, 1866, 

 pi. XXXVIII, fig. 212. — *B. H. Wright, Check List, 1888. — *PiETEL, Conch. 

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

 Lxviii, fig. 6; LXix, figs.l, 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. 



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



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

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

 western, while columhensis occupies a central jjosition in streams of the Gulf drainage. 



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

 Mavgaritana 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. ohesus. 

 I think Lea's name had better be used. 



