A GUIDE 
TO THE 
FOSSIL REPTILES, AMPHIBIANS, 
AND 
FISHES. 
GALLERIES Nos. 3, 4, 5, 11.—FOSSIL REPTILES. 
Reptiles, or “ creeping things,” are appropriately named 
when the existing world alone is considered. It is true 
that most lizards run with great rapidity on land, while 
a few (such as Draco ) glide through the air from branch 
to branch among trees. It is also true that some croco¬ 
diles are both good runners and expert swimmers. All 
these animals, however, progress with a distinctly gliding 
or sinuous creeping motion, and so soon as they stop the 
whole weight of their body rests directly on the ground. 
Their limb-bones are tipped with a cap of cartilage or 
gristle, and are not united by well-fitting joints like those 
of mammals or birds. Consequently, the limbs are used 
merely for progression or balancing, and do not serve either 
for habitual support of the body or for many of the other 
purposes to which they are adapted among the higher warm¬ 
blooded animals just mentioned. 
The predecessors of these “ creeping things,” presumably 
including their ancestors, are revealed by fossils, and prove to 
be remarkably different from those which now survive. During 
the Secondary or Mesozoic Period of the earth’s geological 
history reptiles occupied the place in the economy of Nature 
which has since been usurped by mammals and birds. There 
were land-reptiles, both great and small, with supporting 
B 
