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.
No. 16.—Plesiosaurus dolichodeirus.
Further to the left, on the shore of the Secondary Island, is a restoration of the Plesiosaurus dolichodeirus, or Long-necked Plesiosaurus (No. 16). The head in this remarkable species is smaller, and the neck proportionally longer than in the Plesiosaurus macrocephalus. The remains of the Long-necked Plesiosaur have been found chiefly at Lyme Regis, in Dorsetshire. The well known specimen of an almost entire skeleton, formerly in the possession of His Grace the Duke of Buckingham, is now in the British Museum.
No. 17.—Plesiosaurus Hawkinsii.
The most perfect skeletons of the Plesiosaurus are those that have been wrought out of the lias at Street, near Glastonbury, by Mr. Thomas Hawkins, F.G.S., and which have been purchased by the trustees of the British Museum. A restoration is given by Mr. Waterhouse Hawkins, at No. 17, of a species with characters somewhat intermediate between the Large-headed and Long-necked Plesiosaurs, and which has been called, after its discoverer, Plesiosaurus Hawkinsii.