WEALDEN DINOSAURS. 355 



ORDEn—BmOSJ UBIA. 

 Genus — Hyl^osaurus,* Mantell. 



The third well-marked genus of Dinosaurian Reptiles, referred to in the foregoing 

 division of the present chapter,f is founded upon a large portion of the skeleton of one 

 and the same individual (PI. 35), 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 (Pis. 36 and 37), 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 higher position, or one 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 Hyla^osaurus has not been made known like the Megalosaurus, from detached 

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

 at once brought into the domain of palaeontology by the discovery of the following 

 parts of the skeleton in almost natural juxtaposition (PL 35), viz., the anterior part 

 of the trunk, including ten of the anterior vertebrae in succession (3 — lO), supporting 

 a small fragment of the base of the skull ; the two coracoids (ib., 52), the coracoid 

 extremities of both scapulae (ib., 51), detached vertebrae, several ribs (ib.,^/) more or 

 less complete, and some remarkable parts of the dermal skeleton, including enor- 

 mous vertical plates or spines (ib., d, d), arranged, as it appears, in the form of a 

 median dorsal ridge or crest of singular dimensions. 



This specimen is now in the British Museum. It was discovered in 1 832, in a 

 block of stone, measuring 4| feet by 2| feet, in the Wealden of Tilgate, Sussex. || 



In the fragment of the cranium maybe distinguished the pterygoid elements of the 



* JXaTos, sylvestris, belonging to a wood, aavpos, lizard, 

 t Page 329. 



X 'Crocodile des Marni^res d'Argenton,' Cuvier, Ossemens Fossiles, 8vo, 1836, torn ix, p. 331, pi. 238, 

 figs. 14, 15, 16. 



§ 'Odontography,' p. 287, pi. 62 a, fig. 10. 



II 'Proceedings of the Geological Society,' December 5th, 1832, vol. i, p. 410. 



2e 



