GENUS THRACIA. 7 
4. THRACIA PHASEOLINA, Nosts. The French-bean Thracia. 
(Collect. Mass. Lam.) Mownraeu, pl. 1, fig. 2. 
Pl. II, fig. 4. 
Th. testé ovato-oblongd, transversd, equilatera, ineequivalvi, alba, dia- 
phana, levi; latere posteriore brevi, angulato, truncato. 
Shell ovate, oblong, transverse, equilateral, inequivalve, 
beaks small; that of the left, slightly notched. ‘The valves 
are white, diaphanous and smooth, indistinctly marked with 
strie of increase, rounded at the anterior side, strongly trun- 
cated at the posterior side; the side is bounded outwardly by 
an obtuse angle, pretty prominent, extending obliquely from 
the beak to the Jower part of the shell. The cardinal edge is 
thin, and without teeth; it presents upon the posterior side 
the beaks with a small, internal, short, triangular hollow, in 
which is attached a small internal ligament which is apparent 
externally. The valves are white and shining, internally. 
The anterior muscular impression is elongated, the posterior is 
rounded, and is united to the anterior by a palleal impression, 
deeply notched. ; 
Length 1 inch 4 lines. Width 11 lines. 
Inhabits the road of Cherbourg, in the Channel, the coasts 
of England, at Falmouth; the Mediterranean. This same 
species has been found in the bay of Sea-dogs, but much 
larger. 
This species was known by Petiver, and has been described 
by Lamarck under the name of AmpuipEsMA phaseolina; it ap- 
proaches in its form the Turacia pubescens, but its lightness 
and its size materially distinguish it; it differs also from the 
plicata, for that has very strongly prominent folds, while in the 
A. phaseolina, the striz of increase are scarcely apparent. 
