509 



to have been a terminal one. If it has been articulated with a proximal or middle 

 phalanx, the proximal surface differs from that of any of the distal phalanges in 

 Wombats or Kangaroos by the absence of the trochlear character of such surface in 

 those phalanges. On the plantar surface of this Diprotodon's phalanx, close to the 

 smaller end of the proximal concavity, is an almost flat articular surface (fig. 3, b), pro- 

 bably for a sesamoid bone. Along the inner border of the larger end of the proximal 

 concavity (fig. 3, a) there projects a thick rough tuberosity. Between the plantar 

 end of this tuberosity and the sesamoid (1) surface is a pit big enough to receive the 

 end of a man's finger. In advance of this pit the plantar surface of the phalanx 

 (fig. 2) is crossed by a rough subbilobed ridge for the insertion of a broad and strong 

 flexor tendon ; the flattened surface leading to the distal end of the bone shows a few 

 tubercles. The anconal surface (fig. 1) is less sculptured and is undulate. The trans- 

 verse marginal process (c) projects midway between the proximal and distal ends of 

 the phalanx. The shape of the bone, viewed in profile from the margin sending off 

 the process (c), is shown in fig. 4. This view exhibits the transverse groove (e) which 

 traverses the transversely convex terminal border (fig. 5) of the present singular bone. 

 From the rugged, irregular, tubercular character of the two divisions of this border, 

 with their vascular foramina, it may be concluded that the epidermal case or sheath of 

 the phalanx was more like a hoof than a claw. 



PLATE CXXII. 



Biprotodon australis. 



Fig. 1. Proximal surface of left scapholunar bone. 



Fig. 2. Distal surface of the same. 



Fig. 3. Radial lateral surface of the same. 



Macropus major. 



Fig. 4. Proximal surface of scapholunar bone. 



Fig. 5. Distal surface of the same. 



Fig. 6. Radial lateral surface of the same. 



Diprotodon australis. 



Fig. 7. Plantar surface of left fifth metacarpal bone (?). 

 Fig. 8. Anconal surface of the same. 

 Fig. 9. Distal end of the same. 

 Fig. 10. Proximal end of the same. 



54* 



