78 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
This tooth, in fact, exemplifies the final stage of modification converting the longitudi- 
nally trenchant type of the premolar in existing Carpophagous and Poephagous Marsu- 
pials into the crushing character shown in the homologous tooth of the larger marsupial 
Herbivores. The rest of the molar series in Nototherium differs from that in Diprotodon 
by the smaller size and in the smoother enamel ; and, perhaps, in a little stronger indi- 
cation of the production of the hind part, near the inner end, of the transverse lobes, 
especially of the front one. 
In the incisor series the generic character of Nototherium is strongly marked by the 
form, structure, and nature of the front upper incisor, as before described : and in this 
character we see a nearer approach of Nototherium to Macropus , while the characters 
of the front upper incisor in Diprotodon approximate that genus to Phascolomys. But 
in the number and disposition of the upper incisors, as in the bilophodont molars of 
limited growth, both the large extinct genera retain the poephagous character, as con- 
tradistinguished from the rhizophagous modification shown by the Wombats among the 
existing marsupial Herbivores. 
The lower incisor of Nototherium shows more of the scalpriform character, at least in 
the young individual, than does the upper one ; but, in the full-grown animal, this tooth 
is far from having the proportions and depth of implantation which make it resemble, 
in Diprotodon , the lower pair of scalpriform teeth of the Wombats. In Nototherium 
the lower incisor differs from that in Diprotodon in being narrower, with the enamel 
continued less far or high upon the inner side : this tooth in the young specimen increases 
more rapidly as it sinks in the socket ; but this may be a repetition of an immature 
character, which is shown, in a minor degree, in the jaw of the young Diprotodon described 
and figured in a former Paper *. The widely open base of the growing incisor does not, 
however, extend backward beyond the first molar ; and as this part contracts and solidi- 
fies in the adult, the base of the tooth and its socket are moved more forward, and in 
one species of Noto there (N. inerme) to the anterior half of the symphysis in advance of 
the roots of the first molar. 
I have described, in former works, some detached bones f which from their size 
might, and probably do, belong to the genus Nototherium ; but I have since received 
evidence of extinct species of nearly equal size, and more nearly akin to the Wombat 
and Kangaroo families, to which some of the fossil limb-bones from Nototherian locali- 
ties might possibly belong. I may venture to state that the olecranon of Nototherium 
is as little produced as in the ulna of Diprotodon. But I deem it better to defer further 
illustrations of the osteological character of the present genus until the discovery of 
some portion of the skeleton, under circumstances of juxtaposition, which would warrant 
such further communication to the Royal Society. 
* Philosophical Transactions, 1870, p. 533, PL xlii. fig. 5, it. 
t An astragalus, e. g., in “ Report on the Extinct Mammals of Australia,” op. cit. p. 233, plate 5. figs. 1-6. 
