Animal, the mouth lips wider than long, united for
two-thirds on the upper margin; mantle open; branchiae
four, the outer free posteriorly, and lies in a fold of the
mantle ; the inner are united to the foot anteriorly, the
remainder free ; foot tongue - shaped, and produced
anteriorly.
Unio complanatus, Solander.
Mya complanata, Solander, MSS. Portland Cat. in Brit-
ish Museum. Unio purpureus, Say, Barnes, and others.
CONCHOLOGIA CESTRICA



Shell, heavy, ovate, or rhomboid, inequilateral, round
before, sub-angular behind ; base curved, hinge margin



elevated, sloped posteriorly; beaks not prominent;
epidermis dark olive-green; rayed when young; nacre
varying from white to dark purple, often iridescent;
cardinal teeth thick. H. 2.5, W. 4-4 >^, T. i-i J^, inches.
Very variable.
Station, ponds and running streams. Chester County;
everywhere common.
U. radiatus, Lamarck, An. Sans. Ver., VI., 1819.
r. r<»Hiin>*.
Pig.X8a



Shell, transversely ovate, compressed; anterior end



OS CONCHOLOGIA CBSTRICA.
narrow, rounded; posterior, broad and rounded; dorsal
margin elevated behind the hinge; inferior curved;
beaks moderate; epidermis mostly greenish -yellow,
with numerous broad, dark-green rays; interior yellow-
ish, and iridescent; cardinal teeth bifid, crenulated, and
oblique. H. 2-2 J^, W, 3-4, T, l-iyi. inches.
Station, Schuylkill River, Chester County.
U. cariosus, Say, Nich. Encyc, ist Amer. Ed.,.
1816.
Shell, valves rather thin, sub-oval, inflated; hinge
margin elevated, base curved ; anterior end short,
rounded, posterior narrowly rounded ; the posterior
dorsal slope sometimes with four, or five, fine inter-
rupted wrinkles, and green rays ; beaks at one-fourth
from the anterior end ; yellow or greenish ; inside
bluish-white; cardinal teeth long, compressed, oblique,
crenate. H. 2.5, W. 3.5, L. 1.75, inches.
Station, Schuylkill, Delaware, and Susquehanna Riv-
ers: common.
CONCHOLOGIA CESTRICA, 89

U. ochraceus. Say, Nich. Encyc, ist Amer. Ed., i8l6.
