PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
61 
dible of the inferred female of Nototherium Mitchelli , in every particular in which the 
comparison can be instituted, I am unable to point out any character whereby it can be 
referred to a different species ; and I doubt whether a scrutiny of the original specimen 
would have supplied indications of such distinction. 
Mr. Krefft has favoured me with a pencil-sketch of the base of the incisor (Cut, 
fig. 2, i), of the natural size, from the original fossil, showing the exhaustion of the pulp 
in this tooth of limited growth. 
B. Nototherium Victorias , Ow. — In the specimen of the 
left ramus of the mandible (Plate VII.), liberally trans- 
mitted for my examination by direction of the Trustees 
of the Museum of Natural History in Adelaide, South 
Australia, more of the ascending ramus is preserved than 
in any of the foregoing specimens; and there are differ- 
ences which deserve to be interpreted as specific. 
The specimen was discovered by Mr. Tilgate, of Went- 
worth, South Australia, in freshwater deposits near Lake 
Victoria, in that colony. 
The posterior orifice or entry of the dental canal (fig. 2, o ) 
is on a level with the outlet of the last alveolus (m a), not 
perforating the base of the coronoid above that level as in 
Nototherium Mitchelli. The inflection of the lower border 
(ib. d, d', dJ) begins on a vertical parallel with the hind lobe 
of the penultimate molar (m 2 ), and terminates a little 
behind the vertical parallel of the last alveolus, before 
the horizontal ramus bends upward into the base of the 
ascending ramus. After a subsidence for the extent of base of broken incisor, Nototherium 
an inch and a half, the lower border again begins to be Mitchelli. 
inflected, suddenly (at a e ), and to a greater degree than at any part of the more posterior 
inflection in Nototherium Mitchelli (Plate V. fig. 1, a). The second inflection in the 
present species, at first as thick as the anterior one (viz. 5 lines), quickly thins off as it 
recedes to a plate of 1 line in thickness ( e ) ; which, after the course of about an inch, 
suddenly expands to form the thick inner part (n) of the broad posteriorly flattened 
hind surface of the ascending ramus, supporting the condyle (c). Much of this joint is 
broken away, but both the outer and inner beginnings of its base or “ neck ” remain, 
together with the entire extent of the base of the coronoid plate (fig. 1, q, r), the 
summit of which is also wanting. The concave platform (fig. 2, u) between the fore 
part of the coronoid process and the postalveolar ridge and process has a breadth of 
about an inch and a half ; the process, as usual, has suffered fracture. 
From the back part of the last alveolus to that of the base of the process is 1 inch 
5 lines ; from the same part to the dental orifice ( 0 ) is 2 inches 2 lines : the dental 
Fig. 2. 
