GENUS THRACIA. 5 
2. THRACIA PUBESCENS, Leacu. The Downy Thracia. 
(Collect. Mass. Lam.) 
Pl. II, fig. 2. 
Th. test ovato-oblongd, subdepressa, inequivalvi, equilatera, albo- 
grisea, anticé rotundatd, posticé truncata et angulata; cardine foveolis 
internis -instructo. 
Shell ovate, oblong, transverse, equilateral, inequivalve, 
slightly inflated, of a reddish white color, covered with a 
browner shagreened epidermis, marked with irregular and more 
or less numerous strie of increase. ‘The beaks are short, and 
that of the right valve is notched at its summit to receive that 
of the left valve. ‘The valves are pretty thick, rounded at 
the anterior, and truncated at the posterior side; the same 
side is separated from the upper surface by an obtuse angle, 
which arises from the posterior extremity of the beaks, and 
which descends obliquely as far as the lower extremity of the 
shell. ‘The cardinal edge is rather thin, and destitute of 
teeth ; it presents at the posterior side of the beaks an internal 
hollow, short and thick. ‘The hollow is oblique and bounded 
outwardly by a little ridge, in which is imserted an external 
ligament, whilst another strong ligament is situated in the 
hollows of the valves. Interiorly they are white, smooth and 
polished. ‘There exists upon the anterior side a muscular 
impression, long and very narrow in its middle, very near the 
edge ; the posterior muscular impression is rounded and pretty 
large. 
Length 3 lines. Width 1 inch 10 lines. 
This species, described by Lamarck under the name of ANna- 
TINA myalis, is pretty common in the British seas, principally 
many fragments of shells upon the shores of that state. In my cabinet is a 
single valve, which I picked up several years since upon the coast of 
Maine, at Prout’s Neck, a few miles from Portland,—so that we may infer 
it inhabits the whole coast of New England.—Tr. 
