2^8 



THE SHOULDER GIRDLE. 



[CHAP 



the Ornithorhynchus) curved backward and pointed, sickle- 

 like, at its upper end. Instead of three it presents but two 

 distinct borders and two surfaces ; but the more convex 

 border (s), which is turned forwards and outwards in its 

 natural position, has a small projection (a) near its lower 

 end, which affords attachment to the clavicle, and is evidently 

 the acromion ; and the whole border may be considered to 

 represent the spine. Following the indications afforded by 

 the attachment of the muscles, it appears probable that the 

 whole inner surface represents the prescapular fossa of the 



Fig. 80.— Side view of right shoulder girdle of a young Echidna {Echidna kystrix), §. 

 ss suprascapular epiphysis; ssf subscapular fos^a; pf postscapular fossa; cb 

 coracoid border; gb glenoid border; s spine; a acromion; ess coraco -scapular 

 suture; gc glenoid cavity; c coracoid; ec epicoracoid ; cl clavicle; ic interclav.cle; 

 ps presternum. 



ordinary Mammalian scapula, and that the anterior portion 

 of the outer surface (pf) is the postscapular fossa, and the 

 posterior portion of the same surface (ssf) the subscapular 

 fossa, these two being divided below by a slight ridge (gb), 

 which runs to the edge of the glenoid cavity, and from which 



