BY CHARLES W. DE VIS, B.A. 407 



cannot well refuse to a bone presenting an about equal phase of 

 differentiation a preferential claim on our recognition. Such a 

 bone is the one of which I now submit a cast. The general like- 

 ness it bears to the Diprotodon arm-bone becomes apparent when 

 it is laid beside a cast of the latter humerus. It only remains to 

 invite attention to its characteristic features, premising that its 

 adult condition is evidenced by the state of the epiphyses. 



The ratios of the length and breath of the bone under review 

 to the length of the lower molar series of the Nototheriuin 

 Mitchelli are nearly the same as the proportions between the like 

 elements of comparison in its most gigantic relative ; the proportion 

 of the length to the breadth is exactly the same in the bones of 

 both animals. The head of the Nototherian bone is of the same 

 general form as in Diprotodon, and rises but slightly above the 

 level of the outer tuberosity, in the latter respect differing from the 

 fossil figured in plate (Foss. Mam.), which however, appears to 

 be somewhat imperfect, but agreeing almost precisely with the 

 original of the accompanying cast. The other tuberosity is in both 

 animals well developed, and surmounted by a low fore-and-aft 

 ridge. The rough ridge representing the inner tuberosity is in 

 Nototherium on a lower transverse parallel than in Diprotodon — 

 in the latter the depression between it and the head is on the plane 

 of the outer tuberosity, whereas in the former the highest (most 

 proximal) point of the depression is fully an inch below the 

 tuberosity. The bicipital groove is shallower in Nototherium than 

 in Diprotodon. On the fore side of the shaft the broad ridge 

 falling fi-om the outer tuberosity is much fuller at its origin in the 

 smaller bone, in the larger it curves gently and regularly as it 

 descends, maintains a nearly level summit from nearthe tuberosity to 

 the beginning of the middle fifth of the shaft, then subsiding very 

 gradually disappears midway between the lateral edges of the shaft 

 in Nototherium, commencing at once on the level of the tuberosity 

 it goes straight and full to scarcely the upper third of the shaft, 

 increases for a space in height, then curving suddenly outwards 

 ends abruptly nearer (comparatively) to the head and to the outer 

 edge. The external tubercle has the same situation in both bones, 



