﻿r.AMPSirjs 135 



feebly biangulate posteriorly about midway up ; female shell 

 much narrower in front, considerably expanded behind where 

 it is widely rountled. 



Length (male) 62, height 32, diam. 25 mm. 

 Length (female) 70, height 37, diam. 25 mm. 

 Santee Canal, South Carolina, south to north Florida ; prob- 

 ably west to Mississippi. 



Type locality, Santee Canal, S. C. 

 Unio modioliformis Lea, Tr. Am. Phil. Soc, V, 1834, p. 97, 

 pi. XIII, fig. 40; Obs., I, 1834, p. 209, pi. XIII, fig. 40.— Han- 

 ley, Biv. Shells, 1843, p. 209, pi. xxiii, fig. 37. — Chenu, 

 Man., 1859, II, p. 139, fig. 678.— Simpson, Pr. U. S. N. Mus., 

 XV, 1892, p. 414, pi. Lvi, figs. 2, 3, 6. 

 Margarita (Unio) modioliformis Lea, Syn., 1836, p. 39; 1838, 



Margaron (Unio) modioliformis Lea, Syn., 1852, p. 39; 1870. 



p. 44. 

 Lampsilis modioliformis Simpson, Syn., 1903, p. 559. 

 Unio tenerus Ravenel, Cat., 1834, p. 58. 

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

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

 Unio delumbis KusTER, Conch. Cab., 1861, p. 207, pi. Exix, 



fig. I. 



Doubtfully distinct from L. vihex, though it is generally 

 thinner, more inflated, less rayed, and the female shell is broad- 

 er behind. Some of the young shells can scarcely be separated 

 from the young of L. vibex, and I have seen occasional old 

 specimens that were very hard to place. All the valid speci- 

 mens I have seen are from the Santee Canal, South Carolina. 



Lampsilis gracilior (Lea). 



Shell elliptical or obovate, thin, scarcely subinflated ; beaks 

 not full or high, their sculpture not seen ; posterior ridge almost 

 wanting; surface with somewhat irregular growth lines, but 

 rather smooth and shining, often showing the rest periods quite 

 plainly, olive-brown, or olive-green, feebly rayed or nearly 

 rayless; left valve with two compressed pseudocardinals, the 



