400 BRITISH FOSSIL REPTILES. 



Isle of Wii^ht ; and Brook Point, Isle of Wight. They differ from the convexo- 

 concave vertebrae of StreptospondyJus Cuvieri, from the Lower OoUte and Lias (PI. 20), 

 in their much larger size, and in the absence of the deep pit behind the costal facet. 

 The converging, buttress-like ridges on the sides of the neural arch appear to be de- 

 veloped only in tlie anteriorly convex vertebrae of the dorsal region (Tab. VI, 

 fig. 5, a, b). , 



Cervical vertehra. PI. 31, figs. 1 and 2. PI. 32, figs. 1, 2, and 3. 



The cervical vertebra (PI. 31, figs. 1 and. 2) measures six inches in length. The 

 anterior end of this vertebra is determined by the aspect and position of the 

 zygapophysis (ib. ;:), which, as its articular surface looks obliquely upward and inward, 

 and is on a lower level than the oppositely turned process {z), must be the anterior 

 one. The corresponding extremitv of the centrum (ib. h) is convex ; the opposite 

 extremity, which is somewhat overhung by the higher placed posterior zygapophyses 

 [z), is concave, as shown in fig. 2, c. The whole vertebra is a little crushed obliquely. 

 The fore part of the centrum is further indicated by the position of the parapophysis 

 (ib. figs. 1 and 2, p) or transverse process for the articulation of the head of the rib ; at 

 least, according to the analogy of the Crocodilia, in which it comes off nearer the anterior 

 than the posterior end of the centrum.* Beneath the parapophysis [p] the sides 

 of the centrum are concave, and converge downward to a broad ridge (PI. 32, 

 fig. 2, h), which terminates (at h) the anterior part of the lower surface of the vertebra, 

 and corresponds with the hypapophysis given off from that part in the cervical 

 vertebrae of the Crocodile. f A second concavity, at the upper part of the side of the 

 body, separates the parapophysis from the base of the neural arch ; from which a 

 diapophysis (upper transverse process) is developed for the attachment of the tubercle 

 of the rib. The diapophysis (PI. 31, fig. 1, d) comes off from the under and outer side of 

 the anterior zygapophysis (ib. z). The articular facet of the latter process presents a full, 

 oval figure ; it is slightly raised at its outer part from the horizontal position. There 

 is but little trace of spinous process from the somewhat fractured summit of the 

 neural arch ; this appears to be truncate in front, but has suffered some injury there, 

 permitting the fore part of the neural canal and the whole anterior articular ball to be 

 seen in a direct vertical view (as in figs. 1 and 3, PI. 32). The back part of the 

 neural arch appears to be deeply cleft through the backward production and divergence 

 of the posterior zygapophyses. 



* See Section I, Chapter ii, p. I "JO, pi. Id, fig. 3, p.- {Crocodilus Hastingsia). 

 f lb., figs. 2 and 4. 



