324 PETRIFACTIONS AND THEIR TEACHINGS. CHAP III. 



yield evidence equally conclusive, that the last discovered 

 fossil belongs to a reptile of the same genus. 



VERTEBRA OF THE HYLJEOSAURUS. It is remarkable that 

 detached vertebrae of the Hylseosaurus are very rarely met 

 with. In two of the specimens previously described, there 

 is a considerable number of vertebrae but little removed 

 from their natural juxtaposition : in the collection of de- 

 tached bones from Bolney, but few remains of vertebrse were 

 observed. 



Fortunately, the state of integrity of the anterior, middle, 

 and caudal regions of the spine, in the fossils alluded to, 

 affords ample information as to the structure of the vertebral 

 column in this remarkable genus of saurians. 



The cervical and anterior dorsals are seen in the first dis- 

 covered specimen, and the caudals in the fossil placed imme- 

 diately over it. 



In their general characters the vertebrse of the Hylseo- 

 saurus agree with those of the other Dinosaurians ; there is 

 the same vertical development and expansion of the neural 

 arch and platform in the dorsals, but the bodies are some- 

 what shorter than in the Iguanodon, and both the articular 

 facets are flat and nearly circular, not plano-concave and sub- 

 elliptical, and contracted at the inferior part, as in that ani- 

 mal : there is a depression on each side of the base of the 

 transverse process. 



The cervicals, the visceral aspect of which is shown in the 

 large specimen (Lign. 66), are somewhat flattened below and 

 laterally, so as to present a quadrate form ; and the trans- 

 verse processes, and costal surface for the attachment of the 

 ribs, are displayed ; and several of the ribs are seen lying 

 nearly in their original position. In the dorsal the visceral 

 aspect forms an obtuse ridge, and this gradually becomes 

 broader in the more distal vertebrse : the antero-posterior 

 diameter of the longest dorsal is 2| inches. 



SACRUM OF THE HYL^OSAURUS. Wall-case C. Above the 

 trays containing the large femora of the Iguanodon (ante, 

 p. 237.1), the specimen on the extreme left of the remains 

 of sacra there deposited is a portion of a pelvic arch, which 

 is referred, with much probability, in "Brit. Assoc. Rep." 

 (1841, p. 114), to the Hylseosaurus. This sacrum (labelled 

 consists of the bodies of two vertebrse, two inches 



