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IV. On the Fossil Mammals of Australia. — Part V. Genus Nototherium , Owen. 
By Professor Owen, F.B.S. &c. 
Received May 8, — Head June 15, 1871. 
§ 1. Introduction. — The recognition of the genus which is the subject of the present 
paper was subsequent to that of Biprotodon. So much of the molar teeth as remained 
in the mutilated mandibles* transmitted to me, in 1842, by Sir Thomas Mitchell, C.B., 
from the bed of the Condamine River, indicated their transversely two-ridged character, 
and suggested at first sight that the fossils might belong to some smaller species of 
Biprotodon. Closer scrutiny, however, showed them to be parts of full-grown animals, 
and that they could not be the young of any larger extinct Herbivore. 
Moreover, sufficient of the symphysial or anterior part of one of the mandibular 
fossils remained to demonstrate the absence of any incisor developed as a tusk or defen- 
sive weaponf, such as coexisted with the bilophodont molar teeth in the lower jaw of 
Biprotodon. The small portions of the enamel on the remaining bases of the molars 
(for the crowns of all had been more or less broken away) showed a smoother surface 
than that at the corresponding parts of the molars in Biprotodon. I was therefore led 
to recognize with much interest, in the fossils transmitted by my esteemed friend on 
his return to his duties as Surveyor General of the Colony of Australia, after the 
publication of the workj containing the first notice of Biprotodon , evidence of another 
genus of extinct herbivorous marsupials, second only in bulk to that first discovered, and 
I proposed for the smaller genus the name of Nototherium §. 
Further comparison of the mandibular fossils referable to such genus indicated them 
to have belonged to two species, to one of which (fig. 1, p. 42) I was glad to attach the 
name of its discoverer ( Nototherium Mitchelli) ; the other I proposed to call Nototherium 
inerme , as it afforded evidence of the absence of large incisor tusks. Whether any, or 
of what proportion, or in what number, incisors might have been present in the missing 
fore part of the fractured symphysis could not, of course, be determined ; that which 
remained only gave the negative evidence as to incisors of the relative size and shape 
and persistent growth characterizing the Biprotodon ||. 
* Owen, “ Report on the Extinct Mammals of Australia, &c.,” in Reports of the British Association for the 
Advancement of Science for 1844, 8vo, p. 223, plates 3 & 4. 
f lb. p. 231. 
J ‘ Three Expeditions into the Interior of Eastern Australia,’ vols. i. & ii. 8vo, 1838. 
§ rcros, south, Orjpiov, beast, ‘ Catalogue of the Fossil Mammalia and Aves in the Museum of the Royal Col- 
lege of Surgeons,’ London, 4to, 1845, p. 314. 
|| “ The lower fractured surface exposes the dental canal extending obliquely from without inwards below the 
MDCCCLXXII. G 
