XLIX 



ON A NEW SPECIES OF PLESIOSAURUS FROM STREET,. 

 NEAR GLASTONBURY ; WITH REMARKS ON 

 THE STRUCTURE OF THE ATLAS AND AXIS 

 VERTEBRAE, AND OF THE CRANIUM, IN THAT 

 GENUS. 



Quart. Jour n. Geol. Soc, vol. xiv., 1858,//. 281-294. 



The locality where the Plesiosauriis, which forms the subject of 

 the present brief notice, ^ was obtained is already famous for its rich- 

 ness in such remains. In fact, the limestone beds of the Lower Lias 

 at Street have already yielded at least three species of Plesiosanrus— 

 p. Hawkinsii, P- macrocepliabts, and P- megacephalus ; and it seemed 

 so unlikely that a fourth species should have inhabited the same area, 

 that I was for a long while unwilling to admit the distinctness of the 

 form at present under consideration. 



The evidence which I shall bring forward, however, seems to me 

 to admit of no other conclusion. 



The specimen is a remarkably fine one. The limestone matrix in 

 which it is imbedded being hard and free from pyrites, every part is 

 well preserved ; and the value of the fossil is further enhanced by twO' 

 circumstances : — first, the very slight amount of disturbance which the 

 bones have undergone, so that the vertebrje from the third cervical to 

 the last caudal are all in their natural positions ; secondly, the per- 

 fectly lateral view of the body which is presented. The only important 

 defects are the absence of the paddles, and the flattening and apparent 

 loss of the lower jaw which the head has suffered. 



The total length of the skeleton is about 7^ feet. The left side 



' The specimen will be fully described and figured in the Decades of the Geological 

 Survey of Great Britain. 



