209 
Very fine fossils of this genus are found in Tuscany : an upper valve 
of one of these, which I possess, and which is in very good preserva- 
tion, is nearly five inches in length, and four inches in breadth. 
CXXXV. Plicatula. An inequivalved shell, not eared, with unequal 
beaks, and having the margins plicated : the hinge formed by two 
strong teeth on each valve, and an intermediate pit for the cartilage : 
one mark of attachment in each valve. 
This genus is formed from Spondylus plicatus, Linn, figured by 
Lister, Conch. Hist. Tab. 210, Fig. 44. The shells of this genus are 
not, I believe, known fossil. 
CXXXVI. Gryphcea. An inequivalved bivalve ; the lower valve 
concave, terminated by a beak, and curving upwards and inwards ; 
the upper valve much smaller, like an operculum ; the hinge tooth- 
less, the pit oblong and arched : one impression in each valve. 
Linnaeus was induced, from the curved beak of this shell, to place it 
among the anomiae, as Anomia gryphus. Bruguiere disposed it under 
the genus Ostrea ; but Lamarck considered the termination of the 
beak of the under valve sufficient to allow of its being placed under 
a distinct genus. He notices nine different species ; among which 
is Gryphcea angulata, an individual shell of which, in a recent state, 
is at Paris. 
Fossil shells of this genus are found in considerable numbers indiffer- 
ent parts of England, particularly in Oxfordshire, Gloucestershire, 
Bedfordshire, Wiltshire, Nottinghamshire, and Warwickshire. 
Plate XV. Fig. 3, represents one of these fossils from the banks of 
the Severn, not far distant from Framilode, in Gloucestershire. In this 
specimen, which is of the most common species found in this island, the 
rugae of the lower valve are exceedingly numerous, and consequently 
arranged very closely together. In the fossil shells of this genus, found 
in Warwickshire, a considerable difference is observable : the general 
surface is much smoother ; which, indeed, may have proceeded from 
their having suffered by bowldering. But, besides this circumstance, 
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