84 EXTINCT “MONSTERS 
The Plesiosaur presents, on the one hand, points of resem- 
blance to turtles and lizards,—on the other hand, to crocodiles, 
whales, and, according to some authorities, even the strange 
Ornithorhynchus. But it will be very long before its ancestry 
can be made known. In the mean time we must put it in a 
place somewhere near the fish-lizards, and leave posterity to 
complete what has at present only been begun. It must, how- 
ever, be borne in mind that some of the above resemblances are 
purely accidental, and not such as point to relationship. Because 
their flippers are like those of a whale, it does not mean that 
Plesiosaurs are related to modern whales. It only means that 
similar habits tend to produce accidental resemblances—just as 
the whales and porpoises, in their turn, resemble fishes. To 
make torpedoes go rapidly through the water, inventors have 
given them a fish-like shape ;—in the same way the early forms 
of mammals, from which whales are descended, gradually adapted 
themselves to a life in the water, and so became modified to 
some extent to the shapes of fishes. 
The Pliosaurs, above mentioned, are evidently relations, but 
with short necks instead of long ones. They had enormous heads 
and thick necks. Fine specimens of their huge jaws, paddle- 
bones, etc., may be seen in the fossil reptile-gallery at Cromwell 
Road. One of the skulls exhibited there is nearly six feet 
long, while a hind paddle measures upwards of six and a half 
feet in length, of which thirty-seven inches is taken up by the 
thigh-bone alone. The teeth at the end of the jaws are truly 
enormous. One tooth, from a deposit known as the Kimmeridge 
Clay, is nearly a foot long from the tip of the crown to the base 
of the root. In some, the two jaw-bones of the lower jaw are 
partly united, as in the sperm-whale or cachalot. Creatures so 
armed must have been very destructive. 
