SYNOrsrS of the NAIADES—SfTMrsnx. 559 



expanded posteriorly, the outline sometimes being- almost arcuate on the 

 middle base, and sweeping around in a regular curve to the ligament. 

 Animal with mantle border often spotted, and in the female furnished 

 with flue, well-developed papilla? on the post- ventral region; branchial 

 opejiing large, with many strong papillae; marsupium projecting greatly 

 below the rest of the gills, rounded below ; ovisacs large and distinct. 



fLAMPSILIS MODIOLIFORMIS Lea. 



* Unio modioUformis Lea, Tr. Am. Phil. Soc, V, 1834, p. 97, pi. xiii, fig. 40 ; * Obs., I, 



1834, p. 209, pi. xm, fig.40.— *Ferussac, Guer. Mag., 1835, p. 29.— "Hanley, 

 Test. Moll., 1842, p. 209 ; * Biv. Shells, 1843, p. 209, pi. xxiii, fig. 37.—* Catlow 

 and Reeve, Conch. Nom., 1845, p. 61. — "H. and A. Adams, Gen. Eec. Moll., II, 

 1857, p. 492.— ■ Chenu, Man., 1859, II, p. 139, fig. 678.— *B. H. Wright, Check 

 List, 1888.—* P.etel, Conch. Sam., Ill, 1890, p. 1.59.—* Simpson, Pr. U. S. Nat. 

 Mus., XV, 1892, p. 414', pi. lvi, figs. 2, 3, 6. 



^Margarita ( Unio) vwdioUformis Lea, Syn., 1836, p. 39; 1838, p. 25. 



*Margaron ( Unio) modioUformis Lea, Syn., 1852, p. 39; 1870, p. 44. 



" Unio tenerus Eavenel, Cat., 1834, p. 58.'— * Hanley, Test. Moll., 1842, p. 209; 

 ^ BiT. Shells, 1843, p. 209.—* Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 

 2.58.—* H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 492. 



*Marijarita ( Unio) tenerus Lea, Syn., 1836, p. 39; 1838, p. 25. 



^Margaron {Unio) tenerus Lea, Syn., 1852, p. 39; 1870, p. 44. 



* Unio delumUs Kuster, Conch. Cab., 1861, p. 207, pi. lxix, fig. 1. 



Santee Canal, South Carolina, south to north Florida; probably west 

 to Mississippi. 



tLAMPSILIS GRACILIOR Lea. 



* Unio graeilior ~Lf.a, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 262; *J1. Ac. N. Sci. 



Phila., IV, p. 56, pi. viii, fig. 38; * Obs., VI, p. 56, pi. viii, fig. 38.— * B. H. 



Wright, Check List, 1888. 

 *Margaron (Unio) gracilior Lea, Syn., 1870, p. 45. 

 t * ZJwto o6/«sat.s Lea, Pr. Ac. N. Sci. Phila., IX, 1857, p. 172; *J1. Ac. N. Sci. Phila., 



IV, 1859, p. 197, pi. XXII, fig. 80 ; *Obs., VII, 1859, p. 15, pi. xxii, fig. 80.— *B. H. 



Wright, Check List, 1888. 

 *Margaron (Unio) ohfascus Lea, Syn., 1870, p. 45. 



]S^ear Macon, Georgia. 



t LAMPSILIS VIBEX Conrad. 



* Unio vibex Conrad, New L. and F. W. Shells, 1834, p. 31, pi. iv, fig. 3, p. 72. ^ — 



Ferussac, Guerin Mag., 1835, p. 29.—* Moller, Syn. Nov. Gen., 1836, p. 203.— 

 * Hanley, Test. Moll., 1842, p. 198; * Biv. Shells, 1843, p. 195.— * Chenu, 



'I am not aware that any description ot'Eavenel's species has ever been published. 

 In his catalogue, he gives it this name, and refers to his manuscripts only. Speci- 

 mens that he gave Dr. Lea, which are credited to him from the Santee canal in pencil 

 on the shells, are undoubtedly modioUformis. Other specimens from another locality, 

 which Lea has put with these, and has called Unio tenerus Eavenel, are undoubtedly 

 L. prevostianus Lea. It was these latter specimens which caused me to be mistaken 

 in the identity of Unio tenerus in my papier in Proceedings of the United States 

 National Museum, XV, p. 416. 



^One lot in the Academy of Sciences is the same as the exiguus of Lea, another is 

 the same as Lea"s nashviUianus. Conrad's figure, whicli is not A'ery good, agrees 

 fairly well with the former, but is certainly not the latter. 



