454 
Miscellanea. 
crown, and rather to the outer side of the middle line of the 
grinding surface. 
The length or antero-posterior diameter of the crown is four 
inches ten lines : the breadth of the posterior pair of tubercles is 
two inches eleven lines : the height of the middle eminences from 
the base of the crown is two inches six lines : the tooth is appa¬ 
rently the fourth molar of the left side of the lower jaw. In com¬ 
parison with a corresponding molar in the same state of growth 
of the Mastodon lonyirostris * of Kaup, a cast of which is now 
before me, the Australian molar differs in having the principal 
transverse eminences more compressed antero-posteriorly in pro¬ 
portion to their height, and tapering to sharper summits, which 
however are obtuse and bifid. The breadth of the tooth slightly 
increases to the posterior pair of eminences, whilst in the Mas¬ 
todon lonyirostris and anyustidens the crown maintains the same 
breadth, or more commonly becomes narrower from the anterior 
to the posterior pair of mastoid eminences. 
Other differences observable on a minute comparison are too 
trivial to deserve notice, especially when observed only in a single 
example of a complex molar tooth. In the Australian specimen 
under consideration the mastodontal characters arc unmistakeable, 
and the resemblance to the molar teeth of the Mastodon anyus¬ 
tidens is very close. The specific distinction of the Australian 
Mastodon rests, at present, only on the slight differences pointed 
out in the form of the mastoid eminences and the contour of the 
crown of the molar tooth. 
The question may arise, whether identity of generic characters 
in the molar teeth of an extinct Australian mammal with those 
of the Mastodon can support the inference that the remaining 
organization of the Proboscidian Pachyderm coexisted with such 
a form of tooth ? The analogy of the close mutual similarity which 
exists in the molar teeth of the Tapir, Dinothere, Manatee and 
Kangaroo, suggests the surmise that the mastodontal type of 
molar teeth might also have been repeated in a gigantic Marsu¬ 
pial genus which has now become extinct; and such an idea 
* If this species be distinct from the Mast, angtisfidewi of Cuvier, the molar teeth seem 
to me to offer precisely the same characters. 
