OF TILGATE FOREST. 
^299 
me to decide. The vertehrm are lumbar^ sacral, 
and caudal ; and there are two of the latter an- 
chylosed, and two others disposed to become so ; 
which is remarkable, for in all my skeletons of rep- 
tiles an analogous case is not observable, except 
where the tail has been broken, and then the bone 
becomes united by exostosis, which is not the case 
in these fossils: hence it would seem that these must 
have belonged to an animal making such feeble 
use of the tail, that the vertebra' were occasionally 
anchylosed together. One of the vertebra is of 
the first caudal, viz. of those which su})port the 
largest chevron bones, for it has the articular tu- 
bercles of these bones very strongly marked.” 
( Geolog. Trans, loc. cit.) Caudal vertebra* of this 
kind are figured, “ Tilgate Fossils,” pi. ix. 8. and 
12., and pi. X. fig. 1. : the latter is a fine example, 
displaying the transverse apophyses, and the cavity 
for the medulla : the spinous process is broken off. 
These vertebra are as numerous as those of the 
first system, and attain a large size ; one in my 
cabinet has the following proportions: — height, 
5 inches ; length, 4 inches ; transverse diameter of 
the extremities, 4^ inches. The first caudal are 
deeply impressed by the tubercles of the chevron 
bone : a sacral strikingly coincides with the cor- 
responding bone of the Iguana and Monitor, and, 
if perfect, would measure 10 inches from the ex- 
tremity of one transverse process to the other. The 
detached processes of these bones indicate an enor- 
mous magnitude; a spinous apophysis is 14 inches 
long ; and the extreme sti'ength of a similar process 
belonging to a sacral, is shown in fig. 1. pi. xii. Tilg. 
