193 
very nearly to S. Cultellus, Linn. S. effusus bears some resemblance 
to S. vesper tinus , Linn. S. strigilatus appears to be similar to the 
recent shell of the same name. S. appendiculatus is a small smooth 
elliptical shell, the recent analogue of which is unknown. It derives 
its name from a little process which projects near the beaks. 
Fragments of shells of this genus are found in the Essex cliff. From 
a considerable number of these I have been able to make out only two 
species resembling S. siliqua, Linn, and S. ensis. It is remarkable, 
that in the fossil shell agreeing in the characters of its hinge with S. 
siliqua, a proportionate shortness in its transversal length is observed 
with that of the fossil S. vagina, described by Lamarck. In one valve 
of this species, which I am able to say must have measured nearly an 
inch in its length, from its inferior to its superior edge, the breadth 
from the anterior to the posterior termination is only two inches and 
three quarters. The fossil resembling S. ensis, appears to vary from 
it only in not being quite so much bowed as the recent shell. 
CXXIII. Sanguinolaria. A transverse bivalve, arched on its su- 
perior edge, and gaping a little at its extremities. Two hinge-teeth, 
approximate and articulating, on each valve. 
This genus is exemplified in Sanguinolaria rosea, Solen sanguino- 
lentum, Linn. List. t. 397, Fig. 236. The shells of this genus are 
distinguishable from those of Solen, only by their having two teeth in 
each valve. I am not aware of their having been found fossil. 
CXXIV. Glycemeris. A transverse shell, gaping at both extremi- 
ties : hinge callous, without tooth. This genus is exemplified in G. 
incrassata, Lam. My a siliqua, Chemn. ; but I am not acquainted with 
any species of it as a fossil. 
CXXY. My a. A transverse bivalve, gaping at both ends ; ligament 
internal. The left valve with a hinge tooth, compressed, rounded, 
perpendicular to the valve, and giving attachment to the ligaments. 
Lamarck has not met with any shell of this genus, in a fossil state, 
in the environs of France. 
VOL. III. 
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