58 THE RACES OF THE MASCAEENES. 
surface of the centrum is as much developed as, or even more than, in any of the 
species named. A lateral impression behind the anterior zygapophyses is only slightly 
indicated. Measurements of three specimens will be given below, to show the extent of 
variation in this vertebra. Specimen c belonged to a very large individual, perhaps to 
the same of which a fifth vertebra has been preserved ; and from a comparison with corre- 
sponding vertebrae of other gigantic Tortoises we may assume that this individual had a 
shell about 4^ feet long. 
As in the seventh, so in the eighth vertebra (Plate XIV. fig. B), the neural crest is 
either entirely absent or reduced to a pair of low ridges starting from the centre and 
diverging towards the posterior zygapophyses. In old individuals it is much less distinct 
than in young ones. The diversity between the stout and slender forms is well marked, 
as may be seen from a comparison of the subjoined measurements. 
3rcl vert. 
4th vert. 
5tli vert. 
6th vert. 
7th vert. 
Sth vert. 
Slen- 
Stout. 
Slen- 
Stout. 
Slender. 
Stout. 
Slender. 
Stout. 
a. 
h. 
c. 
Slender. Stout. 
der. 
der. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. mm. mm. 
mm. 
mm. 
mm. 
mm. 
mm. mm. mm. 
Length of centrum . . 
53 
46 
85 
52 
115 
80 
70 
56 
110 69 66 
71 
106 
63 
58 
67 36 30 
Depth of centrum in 
18 
18 
20 
14 
34 
21 
17 
18 
27? 23 18 
25 
50 
25 
26 
44 20 20 
Horizontal width of 
middle of centrum. . 
11 
13 
11 
8| 
22 
13 
10 
12 
25 18 17 
22 
30 
19 
15 
29 16 18 
"Width of anterior con- 
13 
11 
13 
10 
Width of anterior gle- 
noid cavity 
46 
28 
25 
23 
36 26 23 
28 
55 
31 
31 
AVidth of posterior 
condyle 
18 
13 
(broken) 20 
18 
17 
(broken) 26 23 
27 
29 17 16 
Width of posterior 
glenoid cavity .... 
16 
16 
65 
34 
36 
Distance of outer mar- 
gins of anterior zy- 
28 
27 
33 
23 
45 
35 
29 
30 
42 31 30 
33 
62 
40 
29 
57 28 34 
Distance of outer mar- 
gins of posterior zy- 
26 
24 
27 
22 
44 
29 
26 
30 
(broken) 25 24 
27 
70 
36 
33 
72 30 40 
Of the dorsal and caudal divisions of the vertebral column only a small number of 
disjointed vertebrae have been collected. They are of too general a type to require any 
further remark ; and it is quite impossible to form an idea as to the number of the 
caudal vertebrae. 
Limb hones. — In the scapulary (Plate XXIV. fig. C) we notice the acute angle at 
which the scapula and acromium meet ; the body of the scapula proper is slender, tri- 
hedral in form, with its anterior side flat or but little convex. The coracoid becomes 
ankylosed to the scapula at an early age of the animal ; and the neck above its glenoid 
