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 preservation, 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 be- 

 lieve, known fossil. 



CXXXVI. Gryphaa. An inequivalved bivalve; the lower valve con- 

 cave, terminated by a beak, and curving upwards and inwards; the 

 upper valve much smaller, like an operculum ; the hinge toothless, 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. Brnguiere 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 angu- 

 lata, an individual shell of which, in a recent state, is at Paris. 



Fossil shells of this genus are found in considerable numbers in different 

 parts of England, particularly in Oxfordshire, Gloucestershire, Bedford- 

 shire, 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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