THE SHOULDER GIRDLE. 



[CHAP 



curved ; in many cases it has a distinct articular facet on 

 its inner surface for the upper end of the humerus. (See 

 Fig. 78, h.) There is a second spine on the postscapular 

 fossa, and always a well-developed clavicle. 



In the Sloths {Brady podidce, Fig. 79) the prescapular 

 region {of) is larger than the postscapular {pf). The spine 

 arises from little more than the middle third of the bone, 

 vertically. In the young of both genera of this family the 

 acromion is a long strip of cartilage connecting the spine 

 with the end of the coracoid, while the coracoid border of 

 the scapula and the coracoid bone join each other in front, 



Fig. 79 — Right scapula and clavicle of Two-toed Sloth {Cholccpns Jioffnianni), §. 

 af prescapular fossa ; pf postscapular fossa ; ^c glenoid cavity ; a acromion ; 

 c coracoid ; c.r/"coraco-scapular foramen; c/ clavicle. 



converting the coraco-scapular notch into a small oval fora- 

 men {csf). This condition remains in the Two-toed Sloth 

 {CholcEpus) and the extinct Megatherium ; but in Bradypus 

 the acromion gradually becomes reduced in size, losing its 



