THE TASMANIAN NATURALIST. 
67 
process, sloping backwards to a greater degree than Owen's figure 
(Ext. Animals of Aust., Plate 41, Figs* * and 2) ; and in the oriface of 
the dental canal, being raised 25 m.m. above the alveolar border, and 
therefore approximately on a level with the crown of molar No. 3—in 
its present worn state. It also differs in the regions of the symphysis. 
For the proof of mandibular departures from Owen's types compare his 
figures with the phoLograph illustrating this paper. 
Humerus. 
As the humerus is the most important bone in the body of a 
Xototherium, from the standpoint of an osteologist, Professor Owen laid 
the weight of his taxonomic characters upon that bone, and his pub¬ 
lished figures, given upon plate 127 (Ext. Ani. Aust.) detail the humerus 
very exactly to the scale of one half the full size. Our photographs 
make it possible to comparatively study the humerus of 4 N. tas- 
manicum T with Owen's types of 4 N. mitchelli '; while the scale of 
measurements given hereunder supply the information to those who have 
no access to Professor Owen's plates, and are therefore unable to 
conduct such a comparison. 
TABLE OF COMPARATIVE HUMERI. 
N. MITCHELLI 
N. TASMANI- 
CUM. 
Total length of humerus ... = 
400 M.M. 
467 M.M. 
Proximal width ,, ... ... = 
1 22 ?> 
125 „ 
Distal „ „ . 
22 4 » 
175 » 
Least width of shaft 
80 to 82 „ 
62 
Greatest width at unciform process of the 
supinator ridge ... 
140 
9 ° 
Length from unciform process to deltoid 
process ... ... ... ... 
60 
35 >> 
Length of pectoral ridge from the ecto- 
tuberosity to the pectoral process 
2 34 n 
238. „ 
A glance at these measurements will show that the humerus of the 
Tasmanian animal is not only much longer than that of the mainland, 
but is distally much narrower and constricted at the region of the 
unciform process. Another most striking character in the Tasmanian 
bone is the manner in which the 4 unciform' and 4 deltoid processes' 
approach one another, in spite of the extra length of the shaft as a 
whole. The Tasmanian humerus also differs in the region of the 
entepycondylar foramen ; for if it is placed upon a flat surface with 
the thenal side upwards, the actual bony bridge overlaps the edge of 
