RECORDS OF IV. A. MUSEUM. 
[41 
At a point in the mid valley of the tooth, about one-fourth 
from the outer border, a slight swelling or rudimentary link connects 
the two lobes, from this point the surface of the valley slopes 
gradually to the inner and outer confining ridges. 
The unworn enamel seen on the floor of the mid valley and 
near the anterior and posterior ridges is punctate. 
The tooth differs from the upper molars of the two species of 
Diprotodon , D. australis (Owen) and D. minor (Huxley) in having its 
lobes placed more obliquely across the tooth, in the inward pro- 
jection of the posterior lobe and the form of the anterior and 
posterior basal ridges. The upper molars of D. australis (Owen) 
are also much larger. 
Prof. Owen’s genus Nototherium possesses upper molars with 
obliquely directed lobes, anterior and posterior basal ridges, 
enclosed mid valley and enamel punctate when unworn. The 
second upper molar (Mi of Owen’s monographs), as described and 
figured, agrees with the tooth under consideration in size, outline, 
and ornamentation, but the anterior basal ridge is stated to be 
“continued at both ends upon the corresponding border of the 
anterior lobe 1 ” without a tuberosity externally. 
In view of the close resemblance, this molar has been identified 
as belonging to a species of Nototherium and the presence of the 
tuberosity on the anterior basal ridge regarded as an individual or 
specific character. 
The premolar (plate vi., fig. 10) may be described as under : — 
Outline sub-triangular, the outer side being the longest. The 
anterior portion, or talon, is occupied by a cusp having the form of 
an equilateral triangle with one of the angles situated posteriorly 
and a slightly rounded side forming the anterior aspect. The crown 
of the tubercle is worn obliquely, so that the dentine is slightly 
exposed. This surface is considerably lower than the posterior 
portion of the tooth, showing that the opposed tooth of the 
mandible must have had a bulky anterior prominence such as 
shown in all Owen’s figures of D3 of the lower jaw of Nototherium. 
1 Phil Trans. Royal Soc., Part 1, 1872, p. 68; and Ext. Mamm Australia, 
p. 276, 1877 
