PTERODACTYLE. 22o 
air, and shoals of no less monstrous Ichthyo- 
sauri and Plesiosauri swarming in the ocean, 
and gigantic Crocodiles, and Tortoises crawling 
on the shores of the primaeval lakes and rivers, 
air, sea, and land must have been strangely 
tenanted in these early periods of our infant 
world."* 
As the most obvious feature of these fossil 
reptiles is the presence of organs of flight, it 
is natural to look for the peculiarities of the 
Bird or Bat, in the structure of their component 
bones. All attempts, however, to identify them 
with Birds are stopped at once by the fact of 
their having teeth in the beak, resembling those 
of reptiles : the form of a single bone, the os 
quadratum, enabled Cuvier to pronounce at 
once that the creature was a Lizard : but a 
Lizard possessing wings exists not in the pre- 
sent creation, and is to be found only among the 
Dragons of romance and heraldry;! while a 
moment's comparison of the head and teeth 
* Geol. Trans. Lond. N. S. Vol. III. part 1. 
t One diminutive living species of Lizard, (the Draco volans, 
see PI. 22, L.) differs from all other Saurians, in having an ap- 
pearance of imperfect wings, produced by a membranous expan- 
sion of the skin over the false ribs which project almost horizon- 
tally from the back ; the membrane expanded by these false ribs, 
acts like a parachute to support the animal in leaping from tree 
to tree, but has no power to beat the air, or become an instru- 
ment of true flight, like the arm or wing of Birds and Bats ; the 
arm or fore leg of the Draco volans differs not from that of 
common Lizards. 
GEOL. k> 
