34 FOSSIL REPTILES OF DORSET. 



direction behind it, as with reptiles. The ischia are greatly 

 elongated and inclined backwards, and are united in a symphysis. 

 Of this Order Iguanodon, Megalosaurus, Scelidosaurus (Ischyro- 

 saurus) and Cetiosaurus Ornithopsis (?) have been met with in 

 Dorsetshire. 



GENUS IGUANODON. 



The distribution of this remarkable family ranges from the 

 Kimmeridge Clay to the Upper Greensand. It nourished pre- 

 eminently during the Wealden period, and has been met with in 

 England, Belgium, North of France, Germany, and Austria. Three 

 well established species have been found in England Mantellii, 

 Prestwichii, and Seelyi, which latter may possibly prove to be the 

 /. bernissartensis of Boulenger; both have been found in a 

 remarkable Wealden deposit at Bernissart, Belgium. Through the 

 labours of M. Dollo, the Assistant Naturalist of the National Museum, 

 Brussels, we have so full a knowledge of this Dinosaur that there 

 remains only a few and not very important details to make it 

 complete. The nearly perfect skeletons of Iguanodon Mantellii, 

 and bernissartensis are admirably displayed in the Court of the 

 Brussels Museum; the latter stands about fourteen feet nine 

 inches in a nearly erect posture. 



IGUANODON MANTELLII, Mantell. 



The skull of this species is three times longer than its breadth ; 

 the usually large reptilian fossae are reduced to a long narrow slit. 

 Mr. Hulke shows a departure from the reptilian type in the brain- 

 chamber being wholly of bone, and not partly membranous ; also in 

 the obliteration of the sutures. Bird-like, it has a small head, and a 

 long neck. The teeth are very remarkable, resembling those of the 

 existing Iguana in their blade-like form and serrate edges, but 

 differing from it and all other extant reptiles in the internal 

 structure of the teeth, and as they used them for mastication as 

 well as for cutting, the crowns becoming worn down, were constantly 

 replaced by a fresh supply. The front part of the jaws are destitute 

 of teeth. The symphysical end of the mandible hollowed out like 

 a parrot's, and trough-like was surmounted by a distinct cone, the 





