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 a river ; while those of Stonesfield, which contain a some- 

 what similar association of fossils, have as evidently been deposited 

 by a current 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 Hoffman, attained the size of the crocodile, and held an 

 intermediate place between the Monitors and Iguanas. It 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 surftice 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 

 an approach to the modern condition of the earth. 



