368 FOSSIL REPTILES. 



The remains of the four limbs are tolerably entire. The 

 anterior on the right side, and the posterior on the left, scarcely 

 want anything to complete their description. 



These vertebrae, by which the plesiosaurus was first distin- 

 guished, are easily recognized by two small oval fossets, which 

 they all have at their lower face, and by the faces of their 

 bodies, which are very little, if at all, concave, and the middle 

 part of which is even a little convex. 



In general, also, and only excepting a part of the cervical 

 vertebrae, their transverse diameter is greater than their axis, 

 though the difference is less than in the ichthyosaurus. Their 

 annular part is articulated with their body by a suture, and is 

 easily detached from it. It has, in almost all, a spinous apo- 

 physis rather elevated, and articular apophyses, of which the 

 posterior are higher than the anterior, and rest their facets 

 almost horizontally on the anterior ones of the succeeding 

 vertebrae. 



According to the first observation of Mr. Conybeare, it ap- 

 peared to him that at least forty-six of these vertebrae consti- 

 tuted a part of the neck and back ; but it was afterwards 

 found that the number so doing was much greater. 



The anterior vertebrae are a little longer than the others. 

 The only lateral inequality which they show on each side, are 

 two fossae of no great depth, very near each other, placed very 

 low, and which give insertion to the two tubercles of a small 

 cervical rib. 



Between these fossae, and at the lower face, are two small 

 fossets or dimples. These two small holes characterize all 

 the vertebrae of the plesiosaurus, and the cervical as well as 

 the others. In proportion as we proceed to the vertebrae far- 

 ther back, these fossets are seen to approach to, and be con- 

 founded with each other. The portion of the vertebra where 

 they are hollowed, becomes a little salient, assumes a figure 

 vertically more oblong, and remounts by degrees, so as to be- 

 long, in part, to the annular portion of the vertebra, and not 

 merely to the body. 



