THE AGE OF GREAT REPTILES. 
69 
holding its snaky head and long, swanlike neck high 
above the water. This great lizard attained a length 
of not less than seventy feet. 
The student of fossils calls 
it the Plesiosaur, a Greek 
word meaning nearly a 
lizard. 
There were, then, three 
kinds of reptiles: one adapt¬ 
ed to the water, another to 
air, and a third to both air 
and water. Most of them, 
and those, too, the largest 
ones, lived on vegetation, as 
their teeth show. The tracks 
they left in the soft mud are 
handlike. Their vertebrae, 
like those of fishes, were con¬ 
cave on both sides. 
In this age insects began 
to multiply. According to 
good fossils found, beetles, a 
dragon-fly, and other insects 
enjoyed existence in the ex¬ 
tensive though still songless 
forests. Among the shell 
animals in the sea the am¬ 
monites seem to have held 
sway. 
A number of years ago 
some bones were discovered which were said to be 
Fig. 39.— Skeleton of Plesiosaur, found in the Lias strata of England. 
