376 FOSSIL REPTILES. 



The species to which these two kinds of vertebrae may be 

 referred^ the Baron names plesiosaurus pentagonus, and tri- 

 yonus. These appellations, however, he has left open to 

 alteration. 



We have seen that the head of the plesiosaurus was remark- 

 ably small, being less than a thirteenth of the entire body. 

 In the ichthyosaurus the head is one-fourth. Supposing these 

 animals, therefore, to have come in contact, a thing by no 

 means improbable, as they inhabited the same waters, and 

 from their conformation and analogies were evidently fierce 

 and rapacious reptiles, the ichthyosaurus must have been an 

 overmatch for its antagonist, unless the long and flexible neck 

 of the latter gave it some advantages on the score of activity. 

 The plesiosaurus in its movements, and even, in some degree, 

 in its figure, must have resembled the chelonian reptiles, or 

 sea-turtles. Supposing the turtle to be stripped of its shelly 

 armour, the resemblance would be tolerably exact. There can 

 be no controversy respecting the plesiosaurus having been an 

 aquatic animal, from the nature of its paddles, and that it was 

 marine is equally to be concluded in consequence of the debris 

 by which its remains are invariably accompanied. It is pro- 

 bable that, hke the turtle, to whose extremities there is a strong 

 analogy in the plesiosaurus, it may have occasionally visited 

 the coast. Still its mode of loco-motion on terra firmd must 

 have been exceedingly awkward. Neither was it by any means 

 so well fitted for swimming as the ichthyosaurus. Its long neck 

 must have presented a considerable impediment to its progress 

 through the watery element. It is the conjecture of Mr. Cony- 

 beare, that as it breathed the elastic air, and had frequent need 

 of respiration, it generally swam upon or near the surface of 

 the water, arching back its long neck like the swan, and plunging 

 it downwards at the fishes that passed within its reach. He 

 also thinks that it may have lurked in shallow water near the 

 coast, concealing itself among the weeds Thus raising its 

 nostrils to the surface, like the cayman, it might have found a 



