174 BRITISH FOSSIL REPTILES. 



a regular convexity into the under surface of the centrum which, is broad, mode- 

 rately convex across, and concave lengthwise. The border of the front articular 

 surface, c, seems to be naturally bevelled off to a breadth of about half an inch, 

 but becoming narrower near the upper margin of the convexity : this marginal 

 tract may be due to abrasion. The margin of the hind concavity, c', has suffered 

 more obviously from such accidental cause. 



The neural arch, ^, manifests on a striking scale the dinosaurian complexity. 

 It has coalesced with the centrum, leaving no sign of suture. The fore-and-aft 

 extent of its base is 5 inches, thence it expands in length, breadth, and height, to 

 develop the zyg. 22, and di. d, apophyses, and from this bony platform, five strong 

 ridges rise to support and form the neural spine, n s. Of these ridges the anterior 

 pair spring from the prezygapophyses, converge and meet eight inches above their 

 origin ; and, rising for an inch or more, again diverge toward the summit of the 

 spine, which is broken away. The lateral ridges or buttresses are continued with 

 a regular curve from the upper border of the diapophyses, <?, and also divide each 

 into a pair of sharpish ridges, the anterior one being lost upon the side of the 

 spine, the posterior division expanding into a broad, sharp plate, which is thickened 

 as it is lost in the summit of the spine. The breadth of the neural spine, here, is 

 eight inches, but does not exceed four inches at its mid-length, or height. The 

 hind surface of the spine is traversed by a longitudinal medial ridge, »•, com- 

 mencing from the fossa between the post-zygapophyses, increasing in breadth 

 as it rises, and again narrowing or subsiding upon the broad, flattened hind part 

 of the summit of the spine, N s. 



The neural canal, JSFc, shows the usual reptilian, cold-blooded, contracted area : 

 the anterior aperture, of a fuU transversely oval shape, has but 2 inches in long 

 diameter, and 1\ inches vertically. Here the breadth of each neurapophysis is 

 barely 2 inches, but they rapidly thicken or expand as they rise and develop the 

 prezygapophyses, 2. The breadth of each of these processes at its upper or 

 articular end is 3 inches ; the articular surface looks upward with a slight 

 inclination inward and forward. From the centrum to this surface measures 

 5 inches ; the breadth across both surfaces is 6J inches. From the outer side of 

 the pedicle or base of the neurapophysis a narrow ridge ascends, increasing in 

 breadth to the base of the platform external to the prezygapophysis ; it termi- 

 nates abruptly before reaching the fore part of the base or origin of the diapophysis. 

 From the fore part of this ridge are sent off two oblique ridges, subsiding upon 

 the front surface of the supports of the prezygapophyses, and dividing the outer 

 portion of that front surface into three smooth dejoressions, augmenting in size as 

 they ascend. The fore part of the base of the diapophysis begins by a pair of 

 horizontal ridges, one from the outer border of the prezygapophysis, the other 

 from the base of the contiguous vertical ridge, ascending and converging to its 



