x PLEUROREMA 753 
Unio recurvatus Lua, Pr. Ac. N. Sci. Phila., I, 1871, p. 192; 
jiexcoN. Set Phila. VIL, 1874; p. 10,, pl. 11, fig. 6; Obs., 
XIE, 1874, p- 14, pl: 11, fig. 6. 
Umo cireumactus Lea, Pr. Ac. N. Sci. Phila., I, 1871, p. 192; 
jienc IN. sci. Phila, Vill, 1874, plk.av, fig: 11; Obs., XIII, 
taza. p. LOs piv, fis. Li. 
Unio subglobatus Lea, Pr. Ac. N. Sci. Phila., I, 1871, p. 191; 
ie Nese cis baila.” VIL 1874.4... 7; «pls 1, fig:.3; Obs. 
Rell 1874, 'p: ar, pl: he: 3. 
Pleurobema subglebata Simpson, Syn., 1900, p. 751. 
I have united under the oldest name a number of nominal 
species, some of which seem to be slightly identical and others 
are apparently the merest variations. I placed Unio subglob- 
atus by itself as a species in the Synopsis and it has slightly 
higher beaks than the average dolabelloides. But there is a 
complete connection through thorntonii to dolabelloides and to 
circumactus, which has slightly lower beaks and is a little 
less inflated than the rest. 
PLEUROBEMA CRUDUM (Lea). 
Shell subtriangular, subinflated. solid, inequilateral, with full 
high beaks; posterior ridge well developed, rounded, curved ; 
anterior end rounded or very slightly, obliquely truncated 
above; base line nearly straight; post-dorsal outline evenly 
curved from the beaks to the rounded posterior point near the 
base of the shell; surface with irregular growth lines; epider- 
mis cloth-like, brownish or greenish-brown, nearly rayless; 
hinge plate wide; pseudocardinals irregular, torn, two in the 
left valve and three in the right; laterals two in the left valve 
and a double one in the right; beak cavities shallow ; muscle 
scars very small, deep; nacre white, thicker in front. 
Length 46, height 39, diam. 22 mm. 
‘Type locality, French Broad, and Holston rivers, Tennessee ; 
Swamp Creek, Murray County, Georgia. Also Cumberland 
River, Tenn. 
Unio crudus Les, Pr. Ac. N. Sci. Phila., I, 1871, p. 190; Jl. 
Boon. Seto Phila. Villy 1674.apens, pl. iv, fig, 10; Obs., 
XIII, 1874, p. 18, pl. rv, fig. -1o. 
Pleurobema cruda StMPpson, Syn., 1900, p. 757. 
