32 
THE EACES OF ALDABEA. 
Spec. c. Spec. 1. Spec. Tc. 
millim. millim. millim. 
Length of ulna 
195 
110 
142 
Least width of ulna 
31 
18 
22 
Length of radius 
175 
97 
130 
Least circumference of radius 
85 
40 
63 
The general arrangement of the carpal bones does not differ from that of the Gala- 
pagos Tortoises, in the description of which it will be more fully noticed. The scaphoid 
and intermedium are entirely coalesced, even in the younger example ; but all the other 
ossicles are separate. 
Important and striking as the differences are that obtain in the pelvis of the Flat- 
and Round-headed Tortoises, the various species of the latter form (as far as known at 
present) differ but slightly among themselves in this portion of the skeleton. The 
symphysial bridge is strongly compressed, and raised into a trenchant vertical ridge 
below and sometimes above. Singularly, in our large specimen c all the sutures are as 
persistent as in the smaller one, so that the bones readily separate ; in the latter spe- 
cimen all the epiphyses are much less ossified, and the protuberances and processes in a 
much less developed condition, than is observed in other parts of the skeleton of 
this individual : the pelvis appears to be the last part of the skeleton assuming the 
proportions and shape of the adult stage. 
The horizontal diameter of the pelvis (Plate XVII.) exceeds in length the longitu- 
dinal. The iliac bones are broad and stout ; the anterior portion of the pubic bones is 
nearly horizontal, rather obtuse in front, without median crest below ; it emits laterally 
a long strong process, which is obliquely directed outwards. The posterior part of the 
ossa ischii is of great width, scarcely concave above, terminating in a short hamate pos- 
terior process on each side, and provided with an exceedingly high symphysial crest below, 
which, expanding hindwards, forms a large triangular tuberosity. Lateral margin of 
the ossa ischii excised in the shape of a C. Obturator foramina very wide. 
^ Spec. c. 
millim. 
Longest inner vertical diameter of pelvis (from summit of ilium to symphysis) 200 
Longest inner horizontal diameter 230 
Shortest inner horizontal diameter (between ilio-pubic prominences) 140 
Longest diameter of foramen obturatorium 73 
Width of symphysial bridge 35 
Depth of symphysial bridge 60 
Least breadth of posterior portion of ossa ischii 114 
Length of os ilii 183 
Least breadth of os ilii 50 
The shaft of i]ie femur (Plate XIX.) is rather stout, nearly straight, irregularly subte- 
trahedral, narrower in front than behind. The head has an abbreviated ovate form, and 
