Masl 



odon. 



in. 



lines. 



24 







5 



9 



14 



6 



307 



external trochanter, situated below the- great trochanter, which is no f 

 present in the Australian fossil. In the Megatherium and its congeners 

 the flattening of the femur and its transverse breadth greatly surpass 

 the proportions exhibited by the fossil under consideration, or those of 

 the femora of the proboscidian Pachyderms. 



The femur of the Mastodon is that which the Australian fossil most 

 resembles, in being flatter on the posterior than on the anterior surface - 

 Compared with the femur of the Mastodon giganteus, the fossil presents 

 the following differences : it is broader in proportion to its length ; as, 

 for example, 



Australian femur, 

 in. lines. 



From the lower part of the post-trochanterian depression 



to the prominence above the outer condyle .... 180 



Breadth of middle of shaft of femur 5 



Circumference of do. do 13 6 



The surface of the bone below the post-trochanterian depression is 

 more convex in the Australian fossil, and the prominence above the back 

 part of the outer condyle is more developed ; the small trochanter is 

 narrower and longer, and is denned by a groove along its anterior part. 

 The femur in the Mastodon giganteus thins off almost to an edge at the 

 outside of the distal half of the shaft : in the Australian fossil the cor- 

 responding part is broad and convex. The anterior part of the great 

 trochanter rises higher above the level of that part of the femur in the 

 Australian fossil than in the Mastodon. The orifice of the medullary 

 artery is conspicuous in the Australian fossil at the back part a little 

 above the middle of the shaft, and towards the inner side ; the canal 

 slopes upwards : I cannot detect the corresponding orifice in the Mas- 

 todon's femur compared. The Australian fossil exhibits a large medul- 

 lary cavity along the middle of the shaft, with dense parietes an inch 

 thick. 



This specimen appears to be too large in proportion to the molar 

 tooth of the Diprotodon, No. 1487, to have belonged to that animal; 

 and as the molar tooth of a Mastodon, closely resembling the Mastodon 

 angustidens, has been discovered in Australia by Count Strelingsky, the 



2 R 2 



