QUADRULA 819 
QuapRULA ELLIOTTIL (Lea). 
Shell subquadrate or subtrapezoidal, inflated, solid, inequt- 
lateral; beaks only slightly elevated or inflated, their sculpture 
a few strong, somewhat corrugated ridges that curve up 
strongly behind; anterior end somewhat narrowed and round- 
ed; base line lightly curved; dorsal line straight or nearly so; 
posterior end almost squarely truncate ; posterior ridge scarcely 
developed; surface sculptured with uneven concentric ridges 
and with 6 to 8 very strong, oblique folds; these fade out be- 
fore reaching the anterior end and trend in the direction of 
the posterior base; dorsal slope strongly plicate; epidermis 
often bright green in young shells, brownish to blackish in old 
shells ; pseudocardinals low and rather small, ragged and some- 
what split up, two in the left valve and two to three in the 
right ; left valve with two short laterals; right valve with one; 
beak cavities deep, compressed, muscle scars shallow, the an- 
terior partly filled with roughened nacre; pallial line deep, re- 
mote from the border; nacre white, iridescent behind. 
Length 130, height 112, diam. 67 mm. 
Southern Georgia; west to Texas. 
Type locality, Othcalooga Creek, Gordon Co., Ga. 
Unio elliottti Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 262; 
je Ae N= Sct. sPhbila., 1V, 1858) p: 543. pl. vu, fig.. 37; Obs., 
VI, 1858, p. 54, pl. vi, fig. 37—Reeve, Conch. Icon., XVI, 
1864, pl. v, fig. 20. 
Margaron (Unio) elliotiti Lea, Syn., 1870, p. 29. 
Ouadrula elliottii Simpson, Syn., 1900, p. 768. 
T am strongly inclined to believe that this is only a variety 
of perplicata. It is more decidedly quadrate than that species, 
the anterior end is narrowed and the pseudocardinals are 
smaller and less elevated. ‘The Unio atrocostatus of Lea 
seems to be to a certain extent a connecting form. 
QUADRULA UNDULATA (Barnes). 
Shell somewhat elongated, irregularly rhomboid, subcom- 
pressed to subinflated, solid, inequilateral ; beaks only moder- 
ately elevated and inflated, their sculpture a°few strong ridges, 
which are swollen where they cross the posterior ridge; pos- 
