164 LAND TORTOISE FROM AFRICA. 
form in front, its free margin strongly denticulated ; 
the posterior margin of the sternum and carapace more 
or less eroded from frequent contact ; of the five ver- 
tebral plates, the first is pentagonal, broader in front, 
having its anterior angle pointed ; the second, third, 
and fourth, are hexagonal; the fifth is quadrilateral, 
having its basis rounded, and joined to five of the 
marginal plates; in its centre is a marked protube- 
rance, corresponding in situation with the area ; the 
first costal plate is trapezoidal, elongated and round- 
ed anteriorly, its superior margin, where it joins the 
second vertebral plate, much the smallest; the 
second is pentagonal, sometimes heptagonal, the 
third is pentagonal, the fourth is trapezoidal ; the 
marginal plates are twenty-three in number, viz. : 
eleven on each side, and a supracaudal, which is 
single ; the first marginal plate is broad and quadri- 
lateral, the second and third are triangular, having 
their bases rounded, and their apices truncate ; these 
plates are turned slightly upwards at their outer 
margins, hence their upper surface appears some- 
what concave ; the fourth, fifth, sixth and seventh, 
are more or less quadrilateral in shape, longer in 
the vertical than in the antero-posterior direction ; 
they are each distinctly carinated. The marginal 
plates which belong to the moveable portion of the 
carapace, are nine in number ; of these, the first is 
small and somewhat triangular, the base presenting 
upward, and the apex, which is obtuse, downward. 
The remaining plates are irregularly quadrilateral, 
having their outer margins everted, or turned up- 
ward towards the disk ; the supra-caudal is large, 
