SKELETON OF THE CROCODILE. PECTORAL GIRDLE. 263 



scapula, and a ventral bone, the coracoid, with a median 

 unpaired element, the interclavicle ; but there is no separate 

 representative either of the clavicle or precoracoid. 



The scapula (fig. 47, 1) is a large bone, flattened and ex- 

 panded above where it is terminated by an unossified margin 

 the suprascapula, and thickened below where it meets the 

 coracoid. The scapula forms about half the glenoid cavity 

 (fig. 47, 4) for articulation with the humerus, and has the 

 lower part of its anterior border drawn out into a roughened 

 ridge. 



The coracoid (fig. 47, 2) is a flattened bone, much ex- 

 panded at either end ; it bears on its upper posterior -border a 

 flattened surface which forms half the glenoid cavity, and is 

 firmly united to the scapula at its dorsal end. Its ventral end 

 meets the sternum. 



The interclavicle (figs. 46, 1, and 47, 3) is a long narrow 

 blade-shaped bone lying along the ventral side of the sternum ; 

 about a third of its length projects beyond the sternum in 

 front. 



THE ANTERIOR LIMB. 



This is as usual divisible into three portions, the upper 

 arm, fore-arm and manus. 



The upper arm or brachium contains one bone, the 

 humerus. 



The humerus (fig. 48, A, 1) is a fairly long stout bone, 

 considerably expanded at either end. The proximal end or head 

 is evenly rounded and is formed by an epiphysis ossifying from 

 a centre different from that forming the shaft. It articulates 

 with the glenoid cavity. The shaft bears on the flexor surface, 

 at some little distance behind the head, a prominent rounded 

 protuberance, the deltoid ridge. The distal end or trochlea 

 is also formed by an epiphysis and is partially divided by a 

 groove into two convex surfaces ; it articulates with the two 

 bones of the fore-arm, the radius and ulna. 



