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PROFESSOR OWEN ON THE EOSSIL MAMMALS OE AUSTRALIA. 
If, as in the skulls of Mammals generally, we regard the part anterior to the orbits 
as the facial division, which is often the longest, the corresponding part in Nototherium 
offers the strangest and most anomalous form and proportions in the mammalian class. 
It looks like a mere pedunculate appendage to the rest of the skull. Instead of tapering 
to the end, as is usually the case, it expands forward from its base of attachment both 
vertically (Plate II. fig. 1 , is, i 1) and transversely (Plate III. fig. 2 , is, 22"). The vertical 
diameter at the base, or from the depression at the root of the nose to the fore part of 
the maxillary alveolar process, is 4 inches 9 lines ; the same diameter at the fore end, 
from the tips of the nasal bones (15) to the first incisive alveoli (i 1), is 6 inches 6 lines. 
The breadth of the face at the outsides of the antorbital foramina is 2 inches 6 lines ; 
the same dimension across the nasal processes of the premaxillaries (22") is 6 inches. The 
length of the facial part of the skull from the antorbital foramen (Plate II. fig. 1 , 2 >) to 
the fore part of the premaxillary (22') is 5 inches 8 lines. 
The nasal bones (15) appear to expand as they advance, chiefly transversely, for four 
fifths of their extent, then abruptly contract, from their outer borders, to terminate in 
a slightly deflected obtuse apex : their mesial suture appears to lie in a longitudinal chink 
or depression at the anterior third (Plate III. fig. 2 , 15), but the chink does not extend to 
the conjoined apices. The sides of the most expanded part of the external nostril, con- 
tributed by the premaxillaries, swell into low and large, rather rough, tuberosities (22") ; 
between these the upper surface is almost flat, like a platform. 
The premaxillaries (22), which unite with the nasals (15), as in Phascolarctos (Plate II. 
fig. 3 ) and Pliascolomys (ib. fig. 4 ), send their nasal processes upward, outward, and 
forward, where they expand and terminate, each in a tuberosity which projects below and 
a little in advance of the one above mentioned. These tuberosities, with the mesial pro- 
minence of the apices of the nasals, give a trilobate character to the upper boundary of 
the external bony nostril in Nototherium (fig. 2 ), exaggerating that in Pliascolomys (fig. 4 ). 
The premaxillaries (22) contract and descend, below the nasal processes, as vertical 
plates; slightly expanding again, below, to form the alveoli of the incisors, especially of 
the larger anterior pair : the outer surface of these alveoli appears to have been coarsely 
rugous. The inner walls of the alveoli rise, conjoined, as a vertical plate of bone, 
3 inches above the outlets, and extend backward in close contact to form or support the 
beginning of the “ septum narium.” The space between the premaxillary septal plates 
and the superincumbent ends of the nasals is little more than an inch, which gives the 
vertical diameter of the nostril at that part ; its transverse diameter is 4 inches. The 
antero-posterior extent of the alveolar part of the premaxillary is 2 inches 6 lines. The 
fore-and-aft diameter of the outlet of the first incisor is 1 inch 2 lines; the transverse 
diameter is 10 lines. The outlets of the smaller second and third incisors are subcir- 
cular ; each has a diameter of 6 lines. 
The cranial characters above described from casts, drawings, and photographs, I have 
been enabled to test by actual fossils of portions of the upper jaw and skull. 
The first of these is a fragment of a right maxilla with two molars (mi, m 2) in situ. 
