738 PI,EUROBEMA 
the base in a blunt point ; surface nearly smooth in young shells 
but having irregular, concentric growth in the old ones; epi- 
dermis tawny-greenish to tawny-brown, beautifully marked 
with narrow and wide interrupted dark green rays, scarcely 
shining ; left valve with two moderate sized, somewhat stumpy 
pseudocardinals and two curved laterals; right valve with two 
pseudocardinals, the upper small and a double lateral; beak 
cavities impressed; muscle scars very small and very deep; 
nacre silvery white, brilliant, iridescent behind. 
Length 65, height 50, diam. 30 mm. 
Elk, Flint and Duck rivers, Tennessee. 
Type locality, Elk and Flint rivers, Ala. 
Unio maculatus Conrap, New F. W. Shells, 1834, p. 30, pl. 
Iv, fig. 4.—CHENU, Bib. Conch., 1st ser., III, 1845, p. 17, pl. 
I, fig. 7.—Kuster, Conch. Cab. Unio, 1861, p. 216, pl. 
PAXIL ess 2 
Margarita (Unio) maculatus Lea, Syn., 1836, p. 34; 1838, p. 
22% 
Margaron (Umo) maculatus Lea, Syn., 1852, p. 24; 1870, p. 
38. 
Pleurobema maculata SIMPSON, Syn., 1900, p. 747. 
[ cannot be positive as to what Conrad’s species is as his 
figure is rather poor. I have specimens before me from Duck 
River, Tennessee, collected by Jas. H. Ferriss, that agree well 
in form with Conrad's figure and description, but are a little 
brighter and more distinctly painted with green than his figure 
shows. Although specimens of clava somewhat approach this 
in form and painting I consider the two perfectly distinct. 
his shell is shorter, and the pseudocardinals are different, 
being short and radial and not in any case parallel with the 
dorsal line. 
Dr. Lea is inclined to believe (Syn., 1870, p. 38), that Con- 
rad’s Unio maculatus is the same as his own ravenelianus, and 
if this were the case Lea’s name should have precedence. From 
an examination of specimens in the Philadelphia Academy of 
Natural Sciences and Conrad’s figure and description, I am 
forced to differ from Dr. I,ea, as I consider the species close 
to Lamarck’s clava. 
