PROFESSOE OWEN ON MACEOPUS. 431 



produced. The coracoid (fig. 1, c) is represented by a mere tuberosity. The spine 

 (ib. /) begins by an elevation (/") of the dorsal surface near the upper rounded angle 

 of the base (5), and contracts as it rises to form a thin plate, slightly bent toward the 

 infraspinal surface (J) ; and as it continues to rise, inclining to the supraspinal surface, it 

 is continued at the neck of the scapula into an acromial process (e) which extends 1 inch, 

 4 lines from the fore part of the spine, and measures 3 lines across at its free end. 

 This slender acromion is associated with a diminutive clavicle. 



There is a low tuberosity («) below the glenoid cavity, but no trace of that singular 

 production of the fore part of the inferior costa which distinguishes the scapula of 

 Dijjrotodon' . A shallow depression extends along the almost even subscapular surface 

 parallel with the origin of the spine from the opposite surface of the bladebone. 



The clavicle (PL LXXVIII. fig. 3) is three inches in length, with a large reniform 

 syndesmotic articular surface (fig. 4, a) at the sternal end, which is expanded accordingly ; 

 the shaft contracts, becomes compressed, then shghtly broadens at the acromial end, 

 where a narrow ridge on the under surface of the hind border gives attachment to the 

 short ligaments tying it to that part of the scapula. The non-articular surface (fig. 4, b) 

 of the sternal end is excavated. The bone is bent, with the convexity forward. 



The humerus (PI. LXXVII.) of the Rufous, as of other Kangaroos, is slightly bent, 

 with the concavity ulnad ; the tuberosities and ridges are strongly developed, and the 

 entepicondyle is perforated. 



The articular head is large and subhemispheric (ib. fig. 4) ; it is produced anconad, 

 so as to overhang that side of the shaft. The thenal third of the proximal end of the 

 bone is occupied by the two tuberosities and their intervening (bicipital) groove. The 

 ectotuberosity (ib. c) has the form of a long thick ridge ; the entotuberosity (ib. b) is 

 shorter and thicker, strongly convex, and better bears the name of tuberosity ; both 

 rise above the level of the head (ib. fig. 2). The xn-oximal end, showing the above three 

 parts, is still in the state of an epiphysis. 



The proximal third of the shaft is four-sided ; the two broader sides (ib. fig. 2, 1, r) are 

 on the anconal aspect, and meet at the round or obtuse ridge (ib. h) continued from below 

 the overhanging head one third down the bone. The facet on the ulnar side {I) of the 

 ridge is bounded at its lower half by the ridge (e) for the insertion of the " pectoralis." 

 The two facets on the thenal side of the proximal part of the shaft are of unequal 

 breadth ; the broader one (ib. fig. 1, g) is flat, and is bounded below by the ridge e 

 and the stronger deltoid ridge (ib. d), which is continued below the middle of the shaft. 

 The fourth facet (ib./) is the narrowest; it is bounded on the outer (radial) side by the 

 deltoid ridge, which is continued from the ectotuberosity downwards ; a thicker ridge 

 from the entotuberosity (ib. t) subsides upon a roughish surface (ib. fig. 3, v) about one 

 third down the bone. The shaft contracts below the deltoid region, assumes the cylin- 

 drical form for a short extent, and sends ofi" the supinator ridge (ib. figs. 1 & 2, K). 



' Phil. Trans, vol. els. p. 540, pi. slv. 



