102 



MAEINE EEPTILES OP THE OXEOED CLAY. 



to, or nearly to, the posterior end of the centrum, but is separated from the anterior 

 end by a considerable interval. The floor of the neural canal is gently concave from 

 side to side ; it is much narrowed between the surfaces for the neural arch, and widens 

 out considerably in front of and behind them. The neural arches of the sacral vertebrae 

 are not well known, but it can be seen that the outer side of the pedicle had a small 

 surface for union with the upper side of the inner end of the sacral rib («'./"•). 



In the caudal region the centra of the vertebra are shorter than in other parts of the 

 column (PL IV. fig. 6 ; PL V. figs. 6, 7 ; text-figs. 57-59). At the same time they 

 become much wider than high, and in consequence of the presence of large facets for 



Text-fig. 57. 



Middle caudal vertebra of Murcenosaums diirohriveiisis : A, from front ; B, from left side ; 



U, from below. (R. 2863, f Dat. size.) 



c.f., facets for chevrous ; n.a., neural arch ; »•./., facets for caudal ribs. 



the union of the arches and ribs they often present a more or less pentangular outline. 

 The articular faces are rather more concave than in the dorsal and sacral regions. 

 The facet for union with the arch is large, extending nearly the whole length of the 

 centrum ; the floor of the neural canal is concave from side to side and widest behind. 

 The surface [r.f.) for union with the caudal rib is large and nearly circular ; above it is 

 usually continuous with that for the neural arch. Beneath it the sides of the centrum 

 are slightly concave from above downwards, and are separated from the nearly flat 



