46 
THE EACES OF THE MASCAEENES. 
serraia C?). Our specimen has a length of 22 inches and a greatest depth of 8^ inches. 
The thickness of the shell scarcely exceeds 2*5 millims. along the central portions, but 
gradually increases towards the margins. It is that of a fully adult animal, as all the 
sutures have disappeared ; nevertheless we cannot draw a conclusion from this single 
individual as regards the maximum size to which this species attained, because in most 
forms of Testudinata Ave find examples of smaller and larger size, independently of age. 
The general shape of the carapace is very peculiar, and very different from any of the 
other gigantic Tortoises. The anterior three fifths of the shell are very convex and 
much bulged out in every direction ; the posterior two fifths slope towards the much- 
expanded hind margins ; but this slope is rendered very uneven by the fourth and fifth 
vertebral plates being much raised in the middle, and the two elevations being again 
separated from each other by a depression. The margins of the shell also of this 
species are not conspicuously indented. The sutures between the first, second, third, 
and fourth vertebrals are of nearly the same length (3" 11"', 4" 9'", and 4" 6"'), whilst 
the suture between the fourth and fifth vertebrals is only one half that length (2" 3"'). 
The first marginal plate is entirely limited to the anterior vertebral, without extending 
to the adjoining costal. The undivided caudal gently slopes backwards and downwards, 
is much expanded, not turned in or reverted behind; its hind margin is strongly 
curved. It measures h \ in. in its greatest width, and 3 in. 2 lines in length. 
Vertebral column. — A single example of the fifth vertebra of the cervical series is 
preserved (Brit. Mus. no. 39930); there is no means of ascertaining whether it belongs 
to T. triserrata or T. inepta. As regards form, it is nearly intermediate between those 
of T. ])onderosa and T. vosmceri; there is scarcely a trace of a crest on the dorsal 
surface. The individual may have been somewhat inferior in bulk to those whose 
vertebrse are used in the subjoined table for comparison. 
T. ponderosa. T. vosmceri. Mauritian, 
millim. millim. millim. 
Length of centrum 65 75 61 
Horizontal width of middle of centrum 17 14*5 14 
Width of anterior glenoid cavity 28 29 26 
Breadth of posterior condyle 30 20' 5 22 
Scapulary. — Among the numerous specimens three types may be distinctly made 
out : — - 
a. The majority (Plate XXIV. fig. B.) have the distal portion of the I'ig- 1. 
acromium, as well as the proximal half of the scapula, distinctly trihedral, 
the anterior side of the latter being convex, so that a transverse section 
through that part of the scapula represents the following outline (fig. 1). 
The acromium is straight, the coracoid lamina sometimes deeply grooved. 
The whole bone is much more slender than in the Aldabra Tortoises, but 
less so than in the Eodriguez species. Although these specimens differ 
