CHAPTEK VI. 



PLESIOSAURS, OR LONG-NECKED SEA-LIZARDS. 



IN the last chapter we gave a description of the re- 

 mains of those remarkable marine reptiles from the 

 Secondary rocks known as Fish-Lizards, or Short- 

 decked Sea-Lizards ; the general geological relations 

 of the rocks in which their remains occur being there 

 noticed in such a manner that any further allusion to 

 them would be superfluous. The Fish-Lizards were, 

 however, by no means the only reptilian inhabitants of 

 those ancient seas in which the Secondary rocks were 

 deposited. On the contrary, they were accompanied by 

 another group of marine reptiles, equally well adapted 

 for a marine life, but presenting such a totally different 

 type of structure that no one can have any difficulty in 

 distinguishing between the two. So different, indeed, 

 are the skeletons of these two groups of creatures, that 

 with very little instruction every person of ordinary 

 ability ought at once to be able to say to which of the 

 two any single bone he may pick up should be referred. 

 Since the most striking feature in the skeleton of these 

 reptiles, and also one whereby they are very broadly 

 distinguished from the Fish-Lizards, is the great length 



