OOLITIC DINOSAURS. Cy2^ 



served, gives a fore-and-aft extent of ;3j inches, and a vertical dianaeter of 2 inches, from 

 -which the size of the tubercle of the rib may be inferred. 



Restoring the margin of the posterior concavity and the articular surface of the anterior 

 convexity, the length of the centrum of this vertebra would be 1 foot 3 inches. 



The whole of the side of the centrum is occupied by a deep oblong depression which, 

 probably, lodged a corresponding saccular process of the lung. On one side this depres- 

 sion was partially divided by a thin oblique plate (Plate S,C, tig. 1,/, /). I deem it much 

 more probable that the large cancelli obvious at every fractured surface of this vertebra 

 (ib., fig, 2) were occupied in the living reptile by iniossified cartilage, or chondrine, than 

 by air from the lungs, and consequently have no ground for inferring that the whale-like 

 Saurian, of which the present vertebra equals in length the largest one of any Cetacean 

 recent or fossil, had the power of flight, or belonged to either Pterosauria or Aves. 



The neural canal (Plate 81, «) indicates a centre of origin of motory nerves 

 subservient to less energetic, more sluggish, movements than in the volant groups ; 

 movements probably exercised more commonly in the aqueovis than the gaseous atmo- 

 ■spheres ; and it leads to the inference that, when emerging, the huge frame was sustained 

 by the solid earth on limbs of dinosaurian proportions. 



The neural canal at the middle of the vertebra yields 1 inch, 3 lines in diameter, and 

 expands to that of 2 inches at its hinder outlet ; it is here, therefore, one fourth the 

 transverse diameter of the vertebral centrum. 



In a corresponding vertebra of an Eagle (Plate 81, fig. 2) the posterior outlet of the 

 nem-al canal, n, is 4 lines in diameter, that of the end of the centrum, there, being 6 lines 

 in diameter : the relative size of the myelon, here indicated, harmonises with the rapid 

 and powerful exercise of muscles of flight deriving their motive energy from an adequate 

 nervous source. The contrast in the relative size of the myelon and vertebra between 

 the Eagle and the Chondrosteosaur is shown by figs. 1 and 3, n, in Plate 81. 



The specimen here described and figured was obtained from the submerged Wealden 

 deposit on the south coast of the Isle of Wight, and was purchased for the British 

 Museum . 



The extreme modification of structure in the vertebrae of Cliotidrosfeosaurus contrasted 

 with that of the subjects of Plates Gl — 73 leads me to refer them to a distinct genus 

 from BotJiriospondi/lus ; but it is a nearly allied one. 



I had a vertical longitudinal section made of a rolled and worn centrum, of smaller 

 size than the type of Chondrosteosaurus gi(jas, but of similar proportions. It is figured 

 three fourths of the natural size in Plate 82, fig. 2. The black tint indicates the 

 ossified proportion of the vertebral substance ; the lighter tint the chondrosal proportion, 

 filled in the fossil by Wealden marl. 



