300 
VERTEBRAE OF THE REPTILES 
Fossils. A chevron bone, which evidently belongs 
to these vertebrae, is 14 inches in length, and is 
identical with the similar bone in the Iguana. 
The vertebrae of the third system (fig. 3.) correspond 
in many respects with the above, but are more 
decidedly plano-concave, and the body is not sul- 
cated, but is either smooth and rounded, or strongly 
keeled, as in the first system, from which they differ 
in their proportions : one of these, from my cabinet, 
is figured pi. xxi. 27. Ossemens Fossiles, tome v. ; 
and is thus described by M. Cuvier, after alluding 
to the vertebras of the Megalosaurus : — “ Cette 
vertebre, longue de 0*11 me paroit ressembler 
aussi fort exactement a celles de M. Buckland. Un 
caractere remarquable qifon y observe c’est une 
arrete vive ou carene longitudinale a sa face in- 
ferieure : a la grosseur de ses aj)ophyses on pourroit 
croire que c’est une vertebre sacree : elle a, comme 
celles de Stonesfield, beaucoup de rapports avec nos 
vertebres de Honfleur.” The dimensions of a large 
example are — length, 3 inches; height, 5 inches; 
transverse diameter, inches. 
The vertebrae of the fourth system (fig. 4.) are 
very rare, only six or seven having come under my 
observation. They are of the true lacertian type, 
having the articular facets of the body convex pos- 
teriorly and concave anteriorly, and are wider than 
high, as in the Iguana and Monitors, and not in 
the reverse proportions, as in the recent Crocodiles. 
In two large but mutilated cervical, the admeasure- 
ments are as follow: — height of the concave ex- 
tremity, 3J inches ; width of the same, 4^ inches ; 
length of the body, 6 inches. It is not obvious 
