CHAPTER III. 



PART VII. 

 THE PLESIOSAURI. 



ENALIOSAURIANS STRUCTURE OP THE PLESIOSAURUS DISCOVERT OP THE 

 PLESIOSAURUS DOLICHODEIRUS BY MR. CONYBEARE HABITS OF THE PLESIO- 

 SAURI PLESIOSAURUS HAWKINSII PLESIOSAURUS ARCUATU8 PLESIO- 

 SAURUS MACROCEPHALUS PLESIOSAURUS RUGOSUS PLESIOSAURI OF THE 

 WEALDEN. 



EXALIOSAURIANS. As in the tertiary and modern epochs, the 

 predominant terrestrial vertebrata, the mammalia, were repre- 

 sented by aquatic forms of gigantic size which inhabited the 

 sea, so also during the "Age of Reptiles," types of the prevailing 

 class of land quadrupeds swarmed in the ocean, and equalled 

 in numbers, and almost in magnitude, the cetaceans of the 

 present day. These reptilian denizens of the seas of the 

 secondary ages, constitute the order Enaliosauria, (i.e. marine 

 saurians,) which comprises two principal groups ; namely, the 

 Ichthyosauri, or fish-like lizards ; and the Plesiosauri, which, 

 as the name implies, are more nearly allied to the saurians 

 than the animals of the former division; both were air-breathing, 

 cold-blooded, carnivorouSj vertebrate animals, with two pairs 

 of natatory extremities. The Plesiosauri first claim our 

 attention, because the specimens of this genus are deposited in 

 the cases of the Room at present under survey. 1 



The perfect skeletons which will now engage the visitor's 

 attention, present a remarkable contrast with the isolated and 



1 Dr. Buckland's " Bridgewater Treatise" contains an admirable expo- 

 sition of their habits and organization ; and " Brit. Assoc. Rep." 1839, 

 an elaborate osteological investigation of both genera. 



