the Shoulder-girdle of a Plesiosaur. 



337 



surface of the scapula the boundary between the ventral and 

 lateral regions of the bone ; anteriorly it terminates at the edge 

 in a strong outwardly directed tubercle ((!, fig. 2 A) bearing 

 a smooth facet at its summit. 



Fi" 



:^ 



¥ 



A. — Scapula) and c-lavicle of Cryptodidus oxoniensis (adult), from front. 



About ^ nat. size, c, clavicle. 

 B. — Sympliysial surface of left scapula with clavicle (c) in position. About 



I nat. size. 



The surfaces for the humerus and coracoid meet at right 

 angles in an irregular slightly concave line about 6'5 centim. 

 long. The glenoid surface forms half a rather irregular oval 

 measuring 6*5 centim. from the middle of the base to the 

 vertex of the curve, while the coracoidal surface is an isosceles 

 triangle, the sides of which are slightly convex and measure 

 8-2 centim. in length ; the base is formed by tlie line of 

 junction with the glenoid surface. This latter is fairly 

 smooth, while the surface for the coracoid is extremely 

 rugose. 



The dorsal ramus of the scapula is compressed from within 

 outwards and is from 4 to 5 centim. wide at the upper end, 

 which is occupied by a rough depressed surface, to which a 

 small suprascapular cartilage seems to have been attached. 

 The anterior border, which is slightly convex, is rough, as if 

 growth in that direction had not yet ceased. 



