220 MARINE SAURIAN S. 
the living genera of these families, it formed 
a link intermediate between the Monitors and 
the Iguanas. However strange it may appear 
to find its dimensions so much exceeding those 
of any existing Lizards, or to find marine 
genera in the order of Saurians, in which there 
exists at this time no species capable of living 
in the sea ; it is scarcely less strange than the 
analogous deviations in the Megalosaurus and 
Iguanodon, Avhich afford examples of still greater 
expansion of the type of the Monitor and Iguana, 
into colossal forms adapted to move upon the 
land. Throughout all these variations of propor- 
tion, we trace the persistence of the same laws, 
which regulate the formation of living genera, 
and from the combinations of perfect mechanism 
that have, in all times, resulted from their ope- 
ration, we infer the perfection of the wisdom by 
which all this mechanism was designed, and the 
immensity of the power by which it has ever been 
upheld. 
Cuvier asserts of the Mosasaurus that before 
he had seen a single vertebra, or a bone of any 
of its extremities, he was enabled to announce 
the character of the entire skeleton, from the ex- 
amination of the jaws and teeth alone, and even 
from a single tooth. The power of doing this 
results from those magnificent laws of co-exist- 
ence, which form the basis of the science of com- 
parative anatomy, and which give the highest 
interest to its discoveries. 
