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FOSSIL REPTILIA OP THE 



the above-described, exemplifies the cetiosaurian characters of texture (fig. 2, p) also of a 

 contracted antero-posterior extent of the neural arch as it rises from the centrum, 1 and of a 

 partial subsidence of the anterior ball. 2 This vertebra has been crushed and fractured ; 

 the right side is pressed obliquely backward for an inch or so beyond the left side, so that 

 the length of the centrum, measured as it has been squeezed out of shape, exaggerates its 

 original or natural longitudinal diameter. This would not exceed, according to my estimate, 

 eight inches. The vertical diameter of the centrum has also been pressed down beyond 

 its original extent. I put the ball or fore part at 6^ inches, the cup behind at 7 inches, 

 in height. The neural arch, as in the type-vertebrae of Cetiosaurus longus? is retained in 

 anchylosed union with the centrum to the extent shown in Plate X, viz., eight inches. 



A vertically grooved median ridge appears to commence at the back part of the base 

 of the spine. This process is wanting ; it probably would have added a foot to the 

 present vertical extent of the vertebra, which is sixteen inches. Minor projecting parts 

 have been equally broken away, and, as usual, lost in the quarrying or extricating 

 operations. Such fractures occur on both sides of the prominent rim of the hinder cup 

 of the centrum (as at p, fig. 2, PI. X). The singularly naturally compressed upper 

 and middle part of the centrum (ib. /) underlying the neural canal and forming a 

 vertical plate or medial wall of bone, three to four inches in height, and but six lines to 

 eight lines in thickness, has been in part broken away, exposing that canal. The fore 

 and hind outlets of the neural canal are squeezed into a narrow, vertically lengthened, 

 oval shape (ib., fig. 2, n). 



The neurapophysis rises by two buttress-like columns («, n ) which converge as they 

 ascend and overarch the lateral depression /. The base of the neural arch is co- 

 extensive with the centrum, save in so far as the anterior ball may have projected 

 beyond ; but the neurapophysis soon shows, as it rises, the ' short antero-posterior 

 extent/ which is among the characteristics of the genus. 4 One advantage of the 

 fractures, which must otherwise have been got by sections, is the demonstration of the 



1 In the account, illustrated by woodcuts, given by Phillips in his excellent ' Geology of Oxford,' 

 pp. 246 — 294, a vertebra, supposed to be lumbar, the subject of the diagram lxxxviii, p. 257, bas assigned 

 to it the following admeasurement: — "Greatest length from front to back (crushed) 4 6 in." I have 

 found no trunk-vertebrae of the Cetiosaurus from the Kirtlington Oolite so short as this. 



3 In a former ' Monograph ' I remark : — " If, as is very probable, tbe cervical and anterior dorsal 

 vertebrae above described (pp. 22 — 26), and provisionally referred to Streptospondylus, belong to the 

 same reptile as the succeeding vertebrae, here referred to Cetiosaurus, we should then have a gigantic 

 Crocodilian of the peculiar transitional type, as between that order and the Dinosaurian, which is manifested 

 by the " Second Honfleur Gavial " of Cuvier, i.e., with convexo-concave vertebrae at the fore part of the 

 trunk, graduating into plano-subconcave vertebrae with elevated and somewhat complex neural arches, 

 at the middle and back part of the trunk, and with vertebrae sub-concave at both ends in the tail." — 

 ' Monogr. on Wealden Reptilia,' Suppl. II, p. 34, Palaeont. Soc. Vol. for 1857, issued 1859. 



3 " In all these vertebrae the neurapophyses are anchylosed to the centrum," &c. — ' Report,' p. 102. 



4 Monogr. cit. (1859), p. 27. 



