MONOGRAPH 



ON 



THE FOSSIL REPTILIA 



or 



THE WEALDEN FORMATIONS. 



Order— DINOSA URIA. 



Genus — Hylzeosaurus,* Mantell. 



The third well-marked genus of Dinosaurian Reptiles, referred to in a former Mono- 

 graph,! is founded upon a large portion of the skeleton of one and the same individual 

 (T. IV), to which the name at the head of this section has been applied by its discoverer, 

 Dr. Mantell. 



In assigning to this genus a place in the Dinosaurian order, I have been guided by 

 the structure of the vertebral column, especially the sacrum (T. V and VI), and, in 

 placing it after the Megalosaurus, by the following considerations. The distinct alveoli 

 in the jaws of the Megalosaurus, and the resemblance of its teeth to those of two 

 extinct Crocodilians, viz., the Argenton species and the Suchosaurus, seemed to claim 

 for that great carnivorous Dinosaur a position higher, or nearer to the Crocodilian 

 order. In the present genus, which there is good reason for believing to have resem- 

 bled the Lizards more than the Crocodiles in its dental characters, an affinity to the 

 Crocodilia is, however, manifested not only by the structure of the vertebrae and ribs 

 common to it with other Dinosaurs, but likewise by the presence of dermal bones, or 

 scutes, with which the external surface was studded. 



The Hylseosaurus has not been made known like the Megalosaurus, from detached 

 parts of the skeleton successively discovered and analogically recomposed, but was 



* v\alos, sylvestris, belonging to a wood, aavpos, lizard, 

 f Part iii, p 1, Palseontographical Publications for 1856. 



