489 



The chief peculiarity of this bone is its great thickness in proportion to its length. 

 The latter dimension is one fifth less than in the humerus of Macropus major or of 

 Osphranter rufus ; but it is thicker than either at the proximal half of the shaft and 

 its articular extremity ; the distal end is of equal thickness, but the supinator ridge 

 (Plate CXI. k, k'), which is shorter in M. major than in 0. rufus, is still shorter in the 

 extinct Kangaroo which I provisionally ascribe to the genus Phascolagus. In this 

 fossil the anconal end of the articular head is rather more produced and angular, and 

 the upper surface is less convex than in the cited recent species. 



The channel dividing the " head " (a) from the extended ectotuberosity (c, figs. 2 & 5) 

 is less deep ; the bicipital groove (p) is wider ; the ridge (d, d') passing straight down 

 from the fore or palmar end of the ectotuberosity (c) to join the shorter oblique 

 pectoral ridge (e) is sharper, more produced in Phascolagus, and is more patently 

 continued, as a ridge, from that prominent confluence (fig. 1, d') to the bridge (s) 

 spanning the entepicondylar canal. The pectoral ridge (e) is thicker, less sharp, than 

 in the recent species ; such also is the character of the shorter supinator ridge (k, k') in 

 Phascolagus. The anconal surface of the proximal half of the shaft is more convex 

 across, less distinctly divided into facets (marked /, r in fig. 2, Plates LXIX. & CXI.) 

 than in the large cited existing species of Kangaroo. At the distal articular end the 

 radial (n) and ulnar (o) convexities are rather better marked, and the thenal boundary 

 line (fig. 1, t) dips in between them in Phascolagus, is not straight as in Macropus major. 

 or nearly so, as in Osphranter rufus (Plate LXIX. fig. 1). But the chief characteristic 

 of the present fossil is that first noted, viz. its shortness as compared with its thickness 

 or strength. It indicates a Kangaroo as large as, perhaps even larger in the trunk, 

 tail, and hind limbs than the largest living kind, but with proportions of the fore 

 limbs reminding us, in their relative shortness, of those of such small Wallabies as the 

 species of Lagorchestes. 



§ 6. Macropus Titan (Humerus). — A second example of an entire fossil humerus of 

 a Macropode, also from the bed of King's Creek, I owe to my friend Dr. George 

 Bennett, F.L.S. 



It exceeds in length that bone in the largest examples of Macropus major as much 

 as the last-described fossil falls short. But its strength, or thickness, in proportion to 

 the length, is greater than in Phascolagus. 



Two views, front and side, natural size, of this humerus are given in Plate CXIL, 

 and other views of the articular extremities form the subjects of figures 1, 2, & 3, 

 Plate CXIII. I propose to refer, provisionally, this fossil to Macropus Titan. A 

 greater proportion of the shaft is occupied by the deltoid ridge (Plate CXIL d, d'). 

 and a smaller proportion by the supinator ridge (ib. fig. 1, k, k'), than in the recent 

 species ; in this respect the present resembles the smaller fossil humerus (Plate CXI.). 

 The " head " (Plate CXIL fig. 2) is less produced backward than in that species, and 

 is more convex above (Plate CXIII. fig. 3), in both which characters the large fossil 

 more nearly resembles the part in Macropus major and M. rufus. 



