No. 15.—Plesiosaurus macrocephalus.
The first of these has been called, from the relatively larger size of the head, the Plesiosaurus macrocephalus (No. 15), (Gr. macros, long, cephale, head). The entire length of the animal, as indicated by the largest remains, and as given in the restoration, is eighteen feet, the length of the head being two feet, that of the neck six feet; the greatest girth of the body yields seven feet.
No. 15. Plesiosaurus macrocephalus.
Although Baron Cuvier and Dr. Buckland both rightly allude to the resemblance of the fins or paddles of the Plesiosaur to those of the whale, yet this most remarkable difference must be borne in mind, that, whereas the whale tribe have never more than one pair of fins, the Plesiosaurs have always two pairs, answering to the fore and hind limbs of land quadrupeds; and the fore-pair of fins, corresponding to those in the whale, differed by being more firmly articulated, through the medium of collar-bones (clavicles), and of two other very broad and strong bones (called coracoids), to the trunk (thorax), whereby they were the better enabled to move the animal upon dry land.
Remains of the Plesiosaurus macrocephalus have been discovered in the lias of Lyme Regis, in Dorsetshire, and of Weston, in Somersetshire.