IGUANODON. HYL^OSAURUS. 
241 
the remains of the Plesiosaurus, Megalosaurus, 
Hylaeosaurus,* and several species of Cro- 
codiles and Tortoises in these deposits, of a 
period intermediate between the oolitic and 
cretaceous series, but has also discovered in 
Tilgate Forest the remains of the Iguanodon, 
^ reptile much more gigantic than the Mega- 
losaurus, and which, from the character of its 
teeth, appears to have been herbivorous.! The 
teeth of the Iguanodon are so precisely similar, 
in the principles of their construction, to the 
teeth of the modern Iguana, as to leave no 
* The Hylseosaurus, or Lizard of the Weald, was discovered 
in Tilgate Forest, in Sussex, in 1832. This extraordinary Lizard 
'^as probably about twenty-five feet long. Its most peculiar cha- 
racter consists in the remains of a series of long, flat, and pointed 
t>ones, which seems to have formed an enormous dermal fringe, 
ike the horny spines on the back of the modern Iguana. These 
ones vary in length from five to seventeen inches, and in width 
from three to seven inches and a half at the base. Together 
with them were found the remains of large dermal bones, or thick 
scales, which were probably lodged in the skin. 
t The Iguanodon has hitherto been found only, with one ex- 
ception, in the Wealden fresh-water formation of the south of 
England, (PI, 1, sec. 22.), intermediate between the marine 
oolitic deposits of the Portland stone and those of the green- 
sand formation in the cretaceous series. The discovery, in 
^834, (Phil. Mag. July 1834, p. 77), of a large propor- 
lon of the skeleton of one of these animals, in strata of the 
atter formation, in the quarries of Kentish Rag, near Maid- 
the duration of this animal did not cease with 
c completion of the Wealden series. The individual from 
ich this skeleton was derived had probably been drifted to sea, 
t ose which afforded the bones found in the fresh-water depo- 
