Geological Age of Reptiles. 363 
herbivorous mammalia, its teeth, which are of a very peculiar form, 
being in general worn down by the operation of grinding its food. 
The vegetables associated with the remains of the Iguanodon are 
all of a tropical character, and consist of various kinds of ferns, and 
of large plants allied to the dragon-blood plant. ‘The strata in which 
they are found, unlike those of the oolite which preceded, and of the 
chalk which followed these deposites, have clearly been formed in 
the bed of ariver; while those of Stonesfield, which contain a some- 
what similar association of fossils, have as evidently been deposited 
by acurrent which ran into the ocean of the oolite, and carried with 
it remains of terrestrial and fresh-water animals, the shells in the last 
- named strata being, as before remarked, marine, and precisely simi- 
lar to those of the deposites above and below them; while the shells 
of the Hastings’ beds are decidedly fluviatile or lacustral. Besides 
the remains of the reptiles above mentioned, teeth and bones of other 
gigantic oviparous quadrupeds have been found, but the characters 
and relations of the latter have not yet been accurately determined. 
In the extensive marine formation, the chalk, which covers the 
Hastings’ beds, reptiles are less numerous, and the Megalosaurus, 
Iguanodon, and other herbivorous genera, disappear altogether ; no 
traces of their existence occurring after the last named strata were 
deposited. At the epoch of the chalk formation, the Ichthyosaurus, 
and one or more species of crocodile, and marine turtles, existed ; 
and another extraordinary reptile, the Mososaurus, (lizard of the 
Meuse,) or fossil animal of Maestricht, first appears. This crea- 
ture, so celebrated in Oryctology since the first discovery of its head 
and jaws by Hoffinan, attained the size of the crocodile, and held an 
intermediate place between the Monitors and Iguanas. Tt appears to 
have been aquatic, swimming in the manner of a crocodile, and mov- 
ing its vast tail, from side to side, as an oar. With the chalk, the “age 
of reptiles” may be said to terminate—the greater part of the genera 
above noticed appears to have become extinct during the changes 
Which took place on the surface of the earth at that period ; the 
Crocodiles, turtles, &c. alone survived, a new order of things com- 
menced, and in the tertiary formations which succeeded, we perceive 
MM approach to the modern condition of the earth. 
