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FOSSIL REPTILIA OF THE 



cavity of so much of the broad under surface as is preserved (Plate II) is evidently natural. 

 The deep depression (Plate V, fig. 1,/) on each side of the centrum between the par- 

 and di-apophyses recalls a vertebral character of the genus Bothriospondylus. 



The parapophysis (Plate II, fig. 1, p ) projects from the level of the under surface: 

 it commences behind, four inches from that end of the vertebra, as an extension of the 

 lower border of the centrum, curving outward and gaining vertical thickness as the 

 process advances (Plate IV, p ), the fore part of the base of the process occupying the 

 lower vertical half of the centrum, and terminating very near to the beginning of the 

 anterior articular ball. 



The neurapophysis (Plates III, IV, V, ««), which has coalesced with the centrum, 

 begins to rise about two inches in advance of the hinder cup. The part of the broken 

 base there preserved yields a transverse thickness of 3^ inches. Anterior to this the 

 upper surface of the centrum has been abraded to the level of the neural canal, but 

 sufficient is preserved to show that the neurapophysis loses thickness at the middle of the 

 vertebra, and appears to regain it as it approaches the anterior ball (Plate V, fig. 1). 



The base of the diapophysis (Plate V, fig. 1, d) at the part of the neurapophysis pre- 

 served gives a fore-and-aft extent of 3| inches, and a vertical diameter 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 V, fig. 1,/ /). I deem it 

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

 vertebra were occupied in the living reptile by unossified 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 IV, n) 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 aqueous 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 j it is here, therefore, one fourth the 

 transverse diameter of the vertebral centrum. 



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

 neural 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 



