PLEUROREMA 797 
rarely slightly biangulate, ending near the base of the shell 
in a blunt point or feeble biangulation ; epidermis concentric- 
ally wrinkled, dull, greenish-brown, or yellowish-brown, ray- 
less or with faint, broken rays; pseudocardinals low, stumpy, 
two in the left valve and one with vestiges of two others in 
the right ; laterals two in the left valve and a somewhat double 
one in the right; beak cavities shallow; muscle scars small, 
deep; nacre white or lurid whitish. 
Length of type 37, height 24, diam. 16 mm. 
Length 52, height 35, diam. 21 mm. 
Length 50, height 36, diam. 25 mm. 
Kentucky ; Tennessee; western North Carolina. 
Type locality, French Broad River, Asheville, N. C. 
Unio ravenelianus Lea, Tr. Am. Phil. Soc., V, 1834, p. 32, pl. 
ur, fig. 5; Obs., I, 1834, p. 144, pl. 11, fig. 5 —HaNn_ey, Biv. 
Shells, 1843, p. 187, pl. xx, fig. 59—Kuster, Conch. Cab. 
Unio, 1862, p. 269, pl. xcr, fig. 1—Rkreve, Conch. Icon., 
XVI, 1864, pl. xvr, fig. 70. 
Margarita (Unio) ravenelianus Lea, Syn., 1836, p. 22; 1838, 
pe ie: 
Margaron (Unio) ravenelianus Lea, Syn., 1852, p. 26; 1870, 
p. 40. 
Pleurobema raveneliana SIMPSON, Syn., 1900, p. 748. 
Unio decisus Kusier, (part) Conch. Cab. Unio, 1852, p. 41, 
pl. viii, fig. 1. 
I placed this in the group of Pleurobema clava in the Synop- 
sis with considerable doubt. It is an aberrant form having 
some of the characters of the argentewm group, but is quite 
solid and inflated for that assemblage. I now place it near 
P. modica with some hesitation. It is larger and rather more 
inflated than that species and is considerably solider and much 
more inflated than P. pyriforme. 
PLEUROREMA FASSINANS (Lea). 
Shell subelliptical or subrhomboid, convex, rather solid, 1n- 
equilateral; beaks high but not full; posterior ridge well de- 
veloped, inclined to be double, ending in a feeble biangulation 
below the median line; anterior end rounded; base line wel! 
