UNIO 5607 
ble below, ending behind at the median line and base in a wide, 
feeble biangulation; dorsal line irregularly curved; dorsal 
slope obliquely truncated ; base line incurved; surface irregu- 
larly, concentrically sculptured; epidermis dirty greenish-yel- 
low, the posterior part green; right valve with one sub-com- 
pressed pseudocardinal with a vestige of another above it and 
one granular lateral; muscle scars shallow; beak cavity not 
deep; nacre bluish-white, silvery, iridescent behind, thickened 
in front. 
Length 73, height 33, diam. 22 mm. 
Locality unknown. I have no doubt that it belongs some- 
where in the circummediterranean region. 
Unio emarginatus Lea, Tr. Am. Phila. Soc., V, 1834, p. 62, pl. 
IX, fig. 22; Obs., I, 1834, p. 174, pl. 1x, fig. 22—SimpPson, 
Syn., 1900, p. 695. 
Margarita (Unio) emarginatus Lea, Syn., 1838, p. 26. 
Margaron (Unio) emarginatus Lea, Syn., 1852, p. 39; 18760, 
p. 62. 
Lea’s only shell, the type, consists of two opposite, odd 
valves. One of these may possibly be an elongated batavus, the 
other appears distinct. This right valve is irregularly and 
rather strongly concentrically sculptured, it is decidedly arcu- 
ate; the front part of the shell is a dirty greenish-yellow while 
all that part behind the lower angle of the posterior ridge is 
dirty green. The beak is so eroded that the sculpture is not at 
all distinct, but it seems to have the character of members of 
the littoralis group. 
UNIO CARNEUS Kuster. 
Shell subrhomboid or subtrapezoidal, subcompressed to con- 
vex, subsolid or rather thin, quite inequilateral; beaks only 
lightly raised above the dorsal line, not inflated, their sculp- 
ture consisting of numerous, wavy, somewhat broken ridges; 
posterior ridge generally double, the upper angle ending be- 
hind on the median line, the lower reaching to about the base 
of the shell; dorsal line slightly curved, meeting the oblique 
truncation of the dorsal slope with an angle; posterior end 
