58 
PROFESSOR OWEN ON THE EOSSIL MAMMALS OF AUSTRALIA. 
ciable degree different from, those in the subject of Plate V. But, besides the greater 
depth, the outer surface of the jaw is rather less convex vertically beneath the third 
molar (m 1 ) than in the three preceding specimens. Nevertheless I cannot feel that I 
have grounds for propounding any distinction of specific value for the Notothere yielding 
the present fossil. The fracture through the hind part of the symphysis exemplifies 
the complete bony confluence of this part, and the non-existence therein of the wide 
alveolus of a large scalpriform tusk. The transverse fracture anterior thereto at the 
interval between the first and second molars exposes the dental canal, of 4 lines dia- 
meter, situated 2 inches below the outlet of the socket, and 1^ inch above the lower 
surface of the symphysis. 
The fifth mandibular specimen of Notothermm Mitchelli is from the freshwater beds 
traversed by Gowrie Creek, Darling Downs; it was there collected by Henry Hughes, 
Esq., by whom it was presented to the Natural-History Society of Worcester. This 
specimen is chiefly valuable for the more perfect and less worn condition of certain of 
the molar teeth. It consists of a right ramus mutilated (as most of these fossils from 
river-beds are) at both ends. The relative position of the back part of the symphysis 
and of the entry of the dental canal, with the general size and proportions of the best 
preserved parts of the ramus, show the specimen to have belonged to the Notothermm 
Mitchelli ; and it agrees most closely with the more perfect mandible in the Australian 
Museum at Sydney, which I have referred to the female of that species. 
The subject of Plate VI. is an instructive specimen of a mandibular ramus and den- 
tition of a young Notothere; it was transmitted to me, in 1847, by the enterprising 
and unfortunate explorer of Australia, Ludwig Leichhardt, to whom I had been pre- 
viously indebted for the account of the geology of the locality yielding this and other 
remains of extinct Marsupials, which was communicated to the Society in a former 
Memoir *. 
I incline to refer this specimen, from the size of the incisor and of the three anterior 
molars, to Nototlierium Mitchelli. The generic indications in the present fossil will be 
noted in § 4, on the teeth of Notothermm'. the characters of the bone exemplify mainly 
those of immaturity. It consists of a right ramus, which, being figured of the natural 
size in Plate VI., precludes the need of noting dimensions. The antero-posterior extent 
of the three anterior molar-sockets will be seen to agree with that in the mature man- 
dible, Plate V. 
The ascending ramus has been broken away, exposing the formative alveolus of the 
penultimate molar (figs. 3 & 4, m 2 ) and the like cavity at an earlier stage of the last 
molar (ib. m 3). Provision has been made in this cavity for the lodgment of the anterior 
lobe of a tooth of equal transverse diameter (14 lines) with that of the tooth (m 3) 
in place and use in the largest examples of the present species. The dental canal 
(fig. 3, 0 ) exposed by the hinder fracture presents a semielliptic form, 9 lines transversly 
and 3 lines from before backward. The canal undermines, as it were, the shell of the 
* “On the Fossil Mammals of Australia, Part TII. Diprotodon australis, Ow.,” Philosophical Transactions, 
1870, p. 571. 
