CETPTOCLEIDUS OXOXIENSIS. 177 



Tlie scapuhc (sc, PI. X. figs. 1, J a, lb, 1 c ; text-figs. 87-89) are, as usual in the 

 group, triradiate bones, consisting of a backwardly directed bar carrying the articular 

 surfaces for the coracoid and humerus, an upwardly directed process [d.sc), and a ventral 

 ramus (v.sc), which in the adult extends forwards and inwards to the middle line, 

 where it unites in symphysis with its fellow of the opposite side. 



The following description of the scapula is based mainly on the adult shoulder-girdle 

 (E. 2616) figured on PL X. and in text-fig. 87 :— 



The posterior bar is triangular in section ; its inner edge, forming the outer border of 

 the coraco-scapular foramen, is sharp, thickening a little as it approaches the coracoidal 

 surface ; its upper outer border is rounded and passes above into the hinder border of 

 the dorsal ramus or blade. The lower outer border rises into a rough ridge about 2 cm. 

 from the glenoid surface and then runs forwards and outwards, forming on the outer 

 face of the bone the boundary between ventral and lateral regions of the outer and 

 ventral surfaces ; anteriorly it terminates in a strong outwardly directed tubercle 

 having a smooth facet on its summit. The glenoid surface and that for union with 

 the coracoid are at right angles with one another, the line of junction being slightly 

 concave and about 6'5 cm. in length. The form of the glenoid surface is that of half a 

 rather irregular oval, measuring about 6"5 cm. from the middle of its line of union with 

 the glenoid surface of the coracoid to the top of the curve. The surface for union 

 with the coracoid is an isosceles triangle, the sides of which are slightly convex and 

 measure 8*2 cm. in length : the base is the line of union with the glenoid surface. 

 This latter is nearly smooth, while the coracoidal surface is greatly roughened by the 

 presence of irregular pits and ridges. 



The dorsal ramus of the scapula (d.sc.) is compressed from within outwards and is 

 between 4 and 5 cm. wide at its summit, which is occupied by a rough depressed 

 surface to which, in life, probably a small suprascapular cartilage was attached. The 

 anterior border of this ramus, especially on its lower portion, is greatly roughened, 

 probably for the attachment of muscles above, and at its lower end for union with the 

 roughened facet on the outer angle of the clavicle. 



The ventral ramus {v.sc.) is the largest and most important part of the scapula, at 

 least in the adult ; its anterior border is a continuation of the anterior edge of the 

 dorsal ramus ; it is at first rounded and concave as far as the prominent tubercle 

 referied to above, then it becomes relatively sharp and thin, running inwards and 

 forwards to the middle line, where by a sharp curve it passes into the median border 

 with which it makes an angle of about 45°. The posterior border of this region of the 

 scapula forms the anterior and half the inner edge of the coraco-scapular foramen ; it 

 increases in thickness from without inwards and then backwards to the point of union 

 with the anterior prolongation of the coracoid (PI. X. fig. 1 c), the surface for union 

 with which is nearly semicircular and at right angles to the median symphysis. This 

 latter {sym.), occupying the inner face of the thickened posterior prolongation of the 



2a 



