80 EXTINCT: MONSTERS 
Specimens of extinct animals thus set up, give one a much 
better idea than when the bones are all lying huddled together 
on a slab of rock. But it is not always possible to get the 
bones entirely out of their rocky bed, or matrix. 
Fia. 14.—Plesitosaurus macrocephalus. 
It will be remembered that the long and powerful tail of the 
fish-lizard was its principal organ of propulsion through the 
water; and that, consequently, the paddles only played a 
secondary part. They were small, but amply large enough for 
the work they had to perform. But our long-necked sea-lizards 
possessed very short tails. What, then, was the consequence ? 
Obviously that the paddles had all the more work to do, They 
