﻿524 MAKC. AUIT ANA 



docardiiial and behind it a vestige of a second with one lateral ; 

 laterals granular with traces of vertical striation ; muscle scars 

 impressed, the anterior roug^h, the posterior elliptical ; nacre 

 whitish or lurid purplish with numerous pits. 



Length no, height 52, diam. ;^t, mm. 



Length 83, height 40, diam. 22 mm. 



Louisiana ; Ikirnt Corn, Alabama. 



Type locality, New Orleans, La.? 

 Unio hembtli Conrad, Monog., X, 1838, p. 93, pi. li, fig. i. — 



Hanley, Biv. Shells, 1856, p. 383, pi. xxiv, fig. 3. — Sow- 



ERBY, Conch. Icon., XVI, 1866, pi. xxxiii, fig. 172. 

 Margaron (Unio) hembeli Lea, Syn.. 1852, p. 21 ; 1870, p. 32. 

 Margaritana hembeli vSimpson, Syn., 1900, p. 679. — Ortmann, 



Ann. Car. Mus., VIII, 1912, p. 235, figs. 3. 30. 



The general form and texture, the teeth and scars in the 

 cavities of the valves show this to be a Margaritana rather than 

 an Unio. I have examined the animal, which is dark and has 

 the posterior ends of the gills free as is that of M . margariti- 

 fera. Specimens from Burnt Corn, Alabama, are strongly, cor- 

 rugately plicate on the posterior slope and from the posterior 

 ridge fainter radial ridges sweep forward and downward. 

 Some of the shells from near New Orleans are almost smooth. 



