THE GREAT SEA-LIZARDS 
79 
of resemblance, in the backbone, ribs, and skull. Fig. 13 shows 
three different types of lower jaws of Plesiosaurs. The one 
marked C belongs to Plesiosaurus dolichodirus, the species 
represented in our plate. There were no bony plates in the 
eye. Professor Owen thinks that they were long-lived. The 
skin was probably smooth, like that of a porpoise. 
The visitor to the geological collection at South Kensington 
will find a splendid series of the fossilised remains of long-necked 
sea-lizards. They were mostly obtained from the Lias formation 
of Street in Somersetshire, Lyme Eegis in Dorset, and Whitby 
in Yorkshire. Those from the Lias are mostly small, about 
eight to ten feet in length. But in the rocks of the Cretaceous 
period, which was later, are found larger specimens. There is 
a cast of a very fine specimen from the Upper Lias on the 
wall of the Geological Gallery Ko. IV., at South Kensington, 
which is twenty-two feet long. But some of the Cretaceous 
forms, both in Europe and America, attained a length of forty 
feet, and had vertebrae six inches in diameter. The bodies of 
the vertebrae, or “cup-bones,” are either flat or slightly concave, 
showing that the backbone as a whole was less flexible than in 
the fish-lizards. 
Plate V. is from a photograph of a Plesiosaurus skeleton set up 
as if it were that of a living animal in the Natural History 
Museum, in 1892, the bones having been carefully collected by 
I Mr. Alfred N. Leeds, of Eyebury, who has disinterred the 
separate bones of many distinct skeletons of Plesiosaurs from 
I Oxford Clay strata near Peterborough, and to whom great 
credit is due for his laborious work. Quite recently another 
I 
big Plesiosaur skeleton has been mounted in the Natural 
History Museum, near to the above. Though much disturbed 
J by crushing, it shows some remarkable and novel features. 
