204 THE BATH OOLITE PERIOD. CHAP. 



to anterior dorsals, Cuvier, Ossem. Eoss., Plate XXI. figs. 25, 26. 

 These are about eight inches and sixteen inches long, with breadths 

 over the articulating faces of 3*5 and 6-0 inches. In Diagram LIX. 

 fig. 7^ one of the short ribs is given on a scale of one-tenth 

 it is the first or second dorsal. Fig. 6 of the same Diagram re- 

 presents a middle dorsal rib, thirty-four inches long, with a breadth 

 of 6-5 inches over the two heads of the rib, which is formed in 

 one long curved gradually contracting blade, much narrower and 

 deeper than in crocodiles. One may conjecture that the ribs in 

 megalosaurus being as much lacertian as crocodilian in their blade, 

 though not in their mode of articulation, might exhibit the same 

 mixed analogy in respect of number and be more numerous than 

 in living crocodiles, which have never more than fourteen dorsal 

 vertebrae b . 



Lumbar vertebrae of megalosaurus have reached the Oxford 

 Museum from Stonesfield, one of which, figured by Cuvier and 

 Buckland, was regarded by the latter author as a caudal. In 

 Diagram No. LIX., fig. 2 represents this vertebra seen laterally. 

 Shaped as to the body much as the dorsal already described, its 

 sides are very smooth and deeply hollowed; the suture is lower 

 and less arched than in the dorsal vertebra ; the diapophysial spine 

 runs out retrally in an ascending direction (10 from the horizontal) 

 to a length of 5-5 inches from the mesial line, with a breadth 

 of r6. The articulating faces are slightly concave in the middle, 

 and revolute toward the lower edge, the anterior face remarkably 

 so. The height of the articular face is 3*5 inches, the breadth 3*7^ 

 the length of the body 3-9. The neural canal is contracted in the 

 middle. The neural spine is broken. The base of the diapophysial 

 spine extends along the vertebra between the zygapophysial 

 elements. 



In consequence of the revolution toward the lower edges of the 

 articular faces, the interval between these faces is less in the lower 

 than in the upper part. 



The Oxford Museum possesses also a larger lumbar vertebra, 

 which resembles so closely the first of the five which are anchylosed 

 to form the sacral, as to deserve the title of last lumbar. The size 

 is rather greater than that of the first sacral. Height of body 



b Owen, Reports of British Association, 1841, p. 109. 



