ON DIPROTODON 545. 
From these measurements it would appear that No. 2 was about 
one-fourth smaller than Dzprotodon australis, and that No. 1 took 
a place between No. 2 and the latter, but nearer No. 2. The ques-. 
tion of the systematic value of the differences between No. 1 and 
No. 2, on the one hand, and between both of these and Dzprotodon 
australis, now arises. 
In No. 2, the outer surface of the premolar is ridged, and the 
crown of the fist molar is not so broad as it is long. 
In No. 1, the outer surface of the premolar presents simple con- 
vexities, without ridges, and the first molar is distinctly broader 
than long. 
In Diprotodon australis the form of the premolar is not known ;. 
the first molar is somewhat broader than it is long. 
I entertain no doubt that Nos. 1 and 2 are specifically distinct 5. 
and I propose for No. 2 the name Dzprotodon minor. Whether 
No. 1 is specifically distinct from Dzprotodon australis, or whether 
its difference in size is merely sexual, I cannot pretend to say, in 
the absence of any premolar teeth of undoubted J. australts. 
From the very slight extent to which the premolar is worn while 
the first molar is so much abraded, I suspect that the former tooth 
must have persisted for a long while, instead of being pushed out at 
an early period as in many Macropodide. In form and pattern the 
premolar does not depart more widely than the molars themselves. 
from the type found in some Kangaroos, such as Ha/maturus ; and 
the cast of Zygomaturus in the British Museum shows that the upper 
premolar in that animal had an essentially similar structure, though 
it seems to have been somewhat larger in proportion to the molars. 
DESCRIPTION OF PLATE XNI. [PLate 38}. 
Fig. 1. Part of the right upper maxilla of Diprotodon (australis ?); viewed laterally. 
2. The under or oral face of the same fragment. 
3. A premolar tooth, apparently from the opposite maxilla of the samz animal 5. 
viewed from the inner side. 
4. Part of the left upper maxilla of Diprotodon minor ; viewel laterally. 
5. The under or oral face of the same specimen. 
6. Fourth molar, probably of the same specimen of Diprofodon minor. 
VOL. II NN 
