14 ON REMAINS OF AN EXTINCT MARSUPIAL, 



joint of the subject before us with those referred to, notwith- 

 standing that it has much greater affinity with them than with 

 that of any macropod or phascolomys. We must be content to 

 notice its distinctive features. The proximal end of the radius 

 in the kangaroo is characterised by a strong inflection of the neck 

 of the bone ulnad, and by the development from its inner side 

 below the neck of a produced tubercle for the insertion of the 

 biceps tendon. In the fossil radius the inflection is but slight, 

 and there is no tubercle whatever, the tendon being inserted on 

 the strongly rugose surface. It has in the first particular more 

 resemblance to the radius of the wombat, but in this animal the 

 tubercle, though lower than in the kangaroo, stands well out from 

 the surface of the bone. In the macropod the interosseous ridge 

 is faintly marked — in the fossil it is conspicuously developed. 

 At four diameters from the head it causes nearly as great a 

 dilatation of the shaft as in Phascolomys, but whereas in the 

 latter it forms a sharp edge resulting from the gradual bevelling 

 of the whole shaft towards it, in the fossil it is the edge of a 

 longitudinal ridge pinched out, as it were, from the body of the 

 bone from which it is separated on the outer side by an im- 

 pressed channel. In a portion of the ulna, consisting of the head 

 minus the olecranon, we remark the absence of the lesser 

 sigmoid cavity and the imperfection of the greater. The median 

 ridge of the latter is completed only at the posterior edge adjacent 

 to the olecranon — in front there is no deflection of the articular 

 surface towards the position which should be occupied by the 

 lesser sigmoid. The insertion of the brachialis anticus is not as 

 in the Macropodidse into a rough oblique ridge beneath the 

 coronoid process, nor as in Phascolomys into a depression on the 

 inner foot of the sigmoid process, but into a deep pit in the 

 front of the upper edge of that process. The outer surface of the 

 shaft, from the broken edge of the olecranon to the lower end 



of the fragment, is traversed by a broad and rough tract for the 



attachment of the interosseous ligament. 



To sum up — In dentition the animal diverges considerably from 



Nototlierium — more so from I)i]jrotodon — its divergence is towards 



