127 
This bone is represented by one almost perfect specimen ; 
another lacking only the ect-epicondyle and the corresponding 
part of the distal articular surface, and a third comprising the 
ent-epicondylar moiety. While preserving many typical phas- 
colomydian characters, it nevertheless does not possess an 
ent-epicondylar foramen; a very shallow emargination of the 
internal border, however, exists at the level of the lower end of 
the deltoid ridge. The ent-epicondyle itself is relatively less 
internally produced than in the wombat, so that there is less 
asymmetry in the disposition of the two sides of the distal 
extremity. 
The insertional line of the pectoralis, which in the wombat 
forms a low, almost linear, ridge, is, in Phascolonus, a prominent 
angular crest the presence of which confers a distinct angularity 
upon the section of the bone in this region ; the lower end of this 
crest, moreover, where it meets the deltoid ridge, forms a some- 
what swollen tuberosity in place of, as in the wombat, a simple 
angle of meeting. 
Though we can only refer to Owen’s plate of the humerus of 
Nototherium,* the prominence of the pectoral ridge in Phas- 
colonus suggests an approximation to this conspicuous feature in 
the former fossil. The angular ridge, which in the wombat 
extends obliquely from the angle of junction of the pectoral and 
deltoid ridges to become continuous with the proximal end of 
the ent-epicondylar bridge, is, in Phascolonus, represented by its 
upper part only, which soon subsides upon the general thenal 
surface of the shaft, and its direction, moreover, in the latter 
case, is vertical or in a line with the middle of the gap batween 
the radial and ulnar moities of the inferior articular surface. 
RADIUS. 
[Represented by one complete bone and the proximal half of 
another. | 
Length, 174 mm.; breadth (at widest part of distal end), 44mm. 
Wombat :—Length, 100 mm.; breadth, 21 mm. 
The contour of the head more nearly approaches a circular 
figure in Phascolonus than in Phascolomys, which feature is 
partly due to a somewhat less degree of flattening of its 
anconal aspect. In the wombat the proximal border of that 
part of the head which is applied to the lesser sigmoid cavity 
reaches to a slightly higher level than does that of the opposite 
side ; in Phascolonus the conditions are reversed. The interos- 
seous ridge, thetop limit of which in the fossil reaches to the level of 
the lower edge of the bicipital tuberosity, is very prominent and 
rough so that the shaft of the bone is at its broadest at a point 
* Extinct Mamm. of Australia, Pl. exxvii., Text p. 517. 
