PLEUROBEMA TOD 
I have given first the measurements of the type of Lea’s 
Unio tellicoensis and then those of his barnesianus. The latter 
is a younger shell and naturally not quite so inflated as the 
older one. I can see no other difference worthy of mention 
between the two. The form is quite elliptical for a Plewrobema 
of this group, but it has the characteristic texture and epider- 
mis and | believe that it should be placed there. 
PLEUROBEMA PUDICUM (Lea). 
Shell subrhomboid or subelliptical, subinflated, inequilateral, 
rather solid; beaks full and high; posterior ridge strong, nar- 
rowly rounded, sometimes feebly and narrowly biangulate 
below, ending in a slight biangulation near the base of the 
shell: anterior end nearly evenly rounded; base line curved ; 
post-dorsal outline curved, raised in the middle almost to an 
angle; surface with fine, uneven growth lines; epidermis yel- 
lowish-green to tawny-brown, more or less rayed, scarcely 
shining ; pseudocardinals small, uneven, rough, two in the left 
valve and three in the right; laterals curved, two in the left 
valve and a double one in the right; beak cavities not deep; 
muscle scars small, impressed; nacre silvery, white tinted pur- 
ple. 
Tennessee River system. 
Type locality, Florence and Northern Alabama. 
Unio pudicus Lea, Pr. Ac. N. Sci. Phila., IV, 1860, p. 92; Jl. 
Neen: Scuebhila., kV, 1660, po 346, pl tv1, fig. 171;-Obs., 
VIII, 1860, p. 28, pl. tvt, fig. 171—Sowerrsy, Conch. Icon., 
NVI, 1668 pl rxXxxt, fig. 427. 
Margaron (Unio) pudicus Lea, Syn., 1870, p. 37. 
Pleurobema pudica SIMPSON, Syn., I900, p. 751. 
Unio subrotundus Sowerby, Conch. Icon., XVI, 1866, pl. 
XVil, He. 2OD. 
Unio lyonii Lea, Pr. Ac. N. Sci. Phila., IX, 1865, p. 89; Jl. Ac. 
N. Sci. Phila., VI, 1869, p. 259, xxxu, fig. 74; Obs., XII, 
(O00; pidO, pl xxx, fie. 74. 
Margaron (Unio) lyonii Lea, Syn., 1870, p. 56. 
Pleurebema lyonii StMrson, Syn., 1900, p. 751- 
