THE SKELETON 73 
The close connection between the increased efficiency of 
the fore-limbs and the stronger development of the clavicle 
has already been pointed out; and the great physiological 
significance of the clavicle is further shown by the fact, that 
at a certain stage in development it is the strongest por- 
tion of the whole human skeleton and the first to become 
ossified. 
One distinction between the shoulder and the pelvic 
girdle, evident even on superficial comparison, lies in the more 
limited capacity of movement of the latter, which is in turn 
associated with the more limited movements of the hind-limbs. 
But although mechanical causes, connected with the upright 
mode of progression, certainly play a great part in determining 
the condition of the latter, they do not furnish the complete 
explanation, as a similar immobility of the pelvis is found 
in the lowest terrestrial Vertebrates, Reptiles, and Amphibians. 
And further, as in both of these, and especially in the tailed 
Amphibians, no great distinction is found between the mobility 
of the anterior and the posterior hmbs, the first cause of the 
distinction so marked in Man must therefore be sought elsewhere. 
It seems to me to lie, on the one hand, in functional adaptation 
of the pelvis to the requirements of reproduction, and on the 
other, in the fact that the distal part of the pelvis forms the 
functional posterior end of the trunk. At this part of the body, 
where the posterior apertures of the urinogenital and alimentary 
systems occur, a firm framework is needed for the related con- 
vergent viscera. Such a framework would be a predisposing 
factor in the development of the powerful sphincter and limb 
muscles, furnishing the latter with a more extensive and firmer 
surface of attachment, which could further be turned to account 
by the free posterior limbs. | 
The relationships of the pectoral and pelvic girdles to the 
vertebral column are essentially alike in principle. In neither 
case, among terrestrial Vertebrates, is the connection attained 
directly, but always through the intervention of ribs. The 
example, on comparison of the Sea Lion (Ofaria) and Great Ant-Eater (M/yrmeco- 
phaga), in the former of which the prescapular lamina far exceeds in area the rest of 
the blade-bone. The Sea Lion uses its fore-limb as a swimming organ, the Ant-Eater 
for tearing up Termites’ nests and digging. ] 
1 In the scapula of the Veddahs, the greater slant of the spine towards the 
posterior edge, and the consequent greater development of the supraspinous fossa 
(prescapular lamina) as compared with that of Europeans, may be indicated as 
primitive features (Sarasins). 
