EXPLANATION OF THE PLATES. 



PLATE XLVIL 



Represents the crag resting upon chalk, as it actually appears in Bramerton Cliff 

 near Norwich. 



PLATE XLVIIL 



This plate contains a representation of a nearly perfect skeleton of the Plesiosaurus 

 dolichodeirus, described page S81 of this volume. The drawing has been ex- 

 ecuted with extreme care by Mr, Webster. The several parts are described in 

 the accompanying memoir. 



The bones are entirely imbedded in a matrix of lias shale, which, though inter- 

 sected in several places by lines of fracture, has evidently, from the mutual 

 adaptation of the parts, formed one entire mass. Above 20 of the cervical ver- 

 tebrae connected with the head, lie together unbroken. 



We have omitted to state in the memoir, that a second unbroken specimen of 

 the entire vertebral column, from the head to the tail, was found at the same 

 time and place with the one here represented ; and has been presented by Pro- 

 fessor Buckland to the Museum at Oxford. 



PLATE XLIX. 



Restoration of the Plesiosaurus dolichodeirus and Ichthyosaurus communis. 



Fig. 1 . Skeleton of the Plesiosaurus dolichodeirus restored, on the authority of the 



specimen in the preceding plate ; the humero-sternal portion being supplied 



from a specimen in the Oxford collection. 



Fig. 2. The humero-sternal portion as above : see the description in the memoir. 



Fig. 3. Sterno-costal arcs. 



Fig. 4. The pelvis. 



Fig. 5. The humero-sternal portion of the Ichthyosaurus communis, from two 

 nearly perfect specimens in the Oxford collection, collated with a third belonging 

 to H. T. De la Beche, Esq., all agreeing exactly together. 



Fig. 6. Skeleton of the Ichthyosaurus communis, restored from a very perfect speci- 

 men in the collection of the Bristol Institution. 



