PEOFESSOE OWEN ON THE FOSSIL MAMMALS OF AUSTEALIA. 
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The dentine exposed on both lobes of m 2 is transversely linear, with a slight forward 
production in both links (r and s). In m 3 a speck of dentine appears on the inner 
angle of the front lobe (a) : the enamelled ridges of this and the hind lobe show the 
oblique polished tract at their hinder surface. The characteristic proportions of both 
fore and mid links are well shown in m 3, and contrast with the better developed ones in 
the somewhat larger Protemnodon represented by the subject of figs. 11, 12, & 13, 
Plate XXY. 
The last molar in Protemnodon Anak rises, in the outer side view of the mandible, 
clear of the front root of the coronoid process (ib. fig. 7, q). The fore part of the outer 
crotaphyte excavation (fig. 7 ,f) sinks as abruptly from the prominent anterior border as 
in Macropus and Halmaturus ; but the cavity appears to be divided in Protemnodon by 
a curved ridge into an upper (f) and lower (a) channel, the latter being that which 
leads to the large hinder orifice of the dental canal. A similar fracture of the ascending- 
ramus of the mandible in existing Kangaroos would not produce this appearance, but it 
may be due to the minor development and closer approximation to the coronoid plate 
of the base of the inflected mandibular angle in Protemnodon. 
In the depth or vertical breadth of the ramus beneath the last molar and the minor 
degree of vertical convexity of that part, Protemnodon contrasts with the narrower and 
more bulging character of the same part of the jaw in Macropus. It is rather less 
convex, though narrower, in Halmaturus. There is a trace at a , fig. 8, of the beginning 
of the excavation, or lower channel, leading to the intercommunicating aperture and to 
the entry of the dental canal ; but the extent of the inner plate of the mandible, from 
t to a, is not matched by any existing Kangaroo the lower jaw of which I have compared 
with the fossil. 
In the extent of the edentulous and symphysial part of the mandible (ib. fig. 8, l, & J ) 
Protemnodon agrees with Halmaturus rather than with Macropus ; but the syndesmotic 
surface extends nearer to the alveolar outlet of the incisor (i), although it does not 
indicate so firm a union as in Sthenurus (Plate XXII. fig. 6). It extends more in the 
axis of the ramus than in Sthenurus. 
The breadth of the incisor and that of the surface (Plate XXY. fig. 10, i) which 
was opposed to the upper incisors point significantly to a Nototherian tendency. 
The configuration of the crown of the unworn molars (ib. figs. 11-13, m 2, im) 
in a portion of a mandibular ramus of a large Protemnodon Anak supplements the 
illustrations of the mandibular dentition of the species. The fossil was part of an 
individual in which the hindmost molar had recently risen “ into place.” The links 
(fig. 13, r, s ) are more neatly defined in this unworn tooth, which also had not moved 
forward so clear of the coronoid process (fig. 11) as in the older example (fig. 7). 
§ 11. Protemnodon Og, Ow. — The subject of figs. 5 & 6, Plate XXY., with a certain 
increase of size of both mandible and molar teeth, repeats the form and size of the pre- 
molar ( p 3) in Protemnodon Anak , but shows a distinct linear indication of the post- 
basal ridge <7, and a more definite development of the links r and s in the last molar, m 3. 
mdccclxxiv. 2 0 
