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TRANSACTIONS OF THE 



paper, consists of a vertebra of enormous dimensions, 

 possessing characters which enable us to refer it to an 

 extinct genus of the order u Enalio Sauri" of Cony- 

 beare. The animal of which the present remnant con- 

 stituted a portion, existed in a period more recent 

 than that of any of its congeners hitherto discovered. 



On comparison of this vertebra with those of its con- 

 geners, it appears to be generically distinct from them 

 all, but bears a closer approximation to the Plesiosau- 

 rien vertebrae than to any other. The length of the 

 axis of the bone is twice its diameter, being fourteen 

 inches long and seven inches broad. Its sides are 

 slightly concave in the middle, and the weight of the 

 vertebra is forty-four pounds : allowing the individual to 

 possess as many vertebrse as the Plesiosaurus, that is to 

 say sixty-six, independent of those of the tail, the 

 weight of the whole fossil skeleton may be fairly esti- 

 mated as exceeding two tons ; even supposing each ver- 

 tebra to weigh only thirty pounds instead of forty-four, 

 and calculating the weight of the extremities, pelvis, 

 and tail, to be collectively but a little heavier than the 

 spine alone. 



Judging from the position and descending obliquity 

 of the transverse apophyses, and the small size of the 

 canal for the spinal marrow, this vertebra must be re- 

 ferred to the posterior part of the column, and most 

 probably to the lumber region : this opinion is strength- 

 ened by the coalition of the two foramina or fossae, 

 which characterize the inferior aspect of the vertebrse 

 of the posterior part of the column in the spiral bones 



