THE RABBIT. 279 



The anterior or pre-axial edge of the scapula is the 

 coracoid border, its post-axial edge the glenoid border ; 

 a third or acromial border is constituted by the free 

 edge of the large spine which projects from its external 

 face; a fourth or supra-scapular border by its dorsal 

 edge. Its external surface presents a pre-scapular fossa 

 anterior to, and a post-scapular fossa posterior to, the 

 spine : its internal surface constitutes the sub-scapular 

 fossa. The free ventral end of the spine is the acro- 

 mion ; a small process, which projects from it backwards 

 and downwards, is the metacromion. 



82. The clavicle, a small, curved, rod-like bone, attached 

 by fibrous tissue at one end to the sternum, at the other to 

 the acromion. 



Attached to the outer end of the clavicle is a small nodule of cartilage, 

 the meso-scapular segment : attached to its inner or sternal end are 

 two similar nodules, that nearest the clavicle is the procoracoid, 

 the other the omosternum. 



83. If the fore-limb be compared with that of a Lizard 

 (p. 147 X.), it wall be seen that the altered position of 

 the parts in the mammal is due to the following changes : l 

 (i) the distal end of the humerus has become rotated 

 backwards so as to bring the whole limb into a plane parallel 

 with the median vertical plane of the body ; the pre-axial 

 border then becomes external, and the originally dorsal 

 surface looks, on the whole, backwards : (2) the radius 

 and ulna have become fixed in the position of pronation, 

 that is, the distal end of the radius has rotated round the 

 ulna carrying the hand with it : the consequence of this is 

 that while the pre-axial border of the proximal end of the 



1 The changes in position of the vertebrate limbs are best made out 

 on the skeleton of a man or ape, in which the bones are articulated so 

 as to allow cf the natural movements, including pronation and supina- 

 tion, being performed. See Flower, Osteology of the Mammalia, p. 245. 



