54 EXTINCT MONSTERS. 
and fingers were modified into little many-sided bodies, and so 
articulated together as to make the whole limb, or paddle, a solid 
yet flexible structure. In the long-necked sea-lizard, however, we 
find a long arm-bone with a club-like shape; and the two bones 
of the fore-arm are seen to be longer than in the fish-lizard. But 
a still greater difference shows itself in the bones of the finger, as 
we look at a fossilised skeleton (or a drawing of one); for the 
fingers are long and slender, like those of ordinary reptiles. 
There are only five fingers, and each finger is quite distinct from 
the others. This is the reason why the Plesiosaur was considered 
to depart less from the type of an ordinary reptile, and so re- 
ceived its name. Other remarkable differences present themselves 
in the shoulders and haunches, but these need not be considered 
here. The species shown in Fig. 8 had rather a large head. 
It is obvious that such a long slender neck as these creatures 
had could not have supported a large head, like that of the fish- 
lizard. Consequently, we find a striking contrast in the skulls of 
the two forms. That of the Plesiosaur was short and stout, and 
therefore such as could easily be supported, as well as rapidly 
moved about by the long slender neck. Thus we find another 
simple illustration of the “law of correlation,” alluded to on 
p. 6. The teeth were set in distinct sockets, as they are in 
crocodiles, to which animals there are also points of resemblance, 
in the backbone, ribs, and skull. Fig. 7 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-Regis in Dorset, and Whitby 
in Yorkshire. Those from the Lias are mostly small, about eight 
