PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
275 
Atlas. The proportion of p 3 in Protemnodon is much the same as in the Bettongs * ; 
it is not equal to that in Dendrolagus dorcocephalus f. As in this Tree-Kangaroo, the 
lower molars, like the upper ones, retain the Macropodal bilophodont character. But 
the lower premolar of Protemnodon shows no indication of the three-lobed division 
which is marked on the outer surface of the crown of that premolar of Dendrolagus. 
It is rather more like that in the Potoroos, though the indications of vertical grooves 
and ridges on the compressed part of the crown between the slight fore and hind 
thickened ends are feebler. 
The greatest height of the crown of the premolar, which is at the fore part (Plate 
XXV. figs. 3, 5, 7, & 8, p 3), is but half the antero-posterior diameter ; the utmost 
thickness (at the back part of the crown) (ib. fig. 2) is less than the height. The free 
or trenchant margin is straight, and runs nearly parallel with the base of the crown. 
The fore border is subtrenchant, the hind one flattened, and closely adpressed against 
the contiguous molar. The fore part is defined behind by the subsidence of the narrower 
following part of the crown on the outer side (Plate XXY. fig. 3, p 3), and, less definitely, 
by the foremost of the shallow vertical grooves on the inner side (ib. fig. 8). The base 
of the fore part of the crown bulges forward beyond the anterior root. The hind 
part of the crown slightly expands, but is not defined, like the front expansion, from 
the rest of the crown. A feeble indication of a “ cingulum ” runs along the outer side 
of the base of the crown, and is more dubiously represented by a slight smooth out- 
swelling along the base of the inner surface. The tooth is implanted by two antero- 
posterior, slightly divergent, fangs. 
§ 10. Protemnodon Analc, Ow. — The subject of Plate XXV. figs. 1 & 2, the type 
specimen on which the species Macropus ( Protemnodon ) Analc was founded J, is a 
portion of a left mandibular ramus, including the molar series. All the teeth of the 
permanent dentition are in place, and from the degrees of wear of their crowns it may 
be inferred that the foremost (p 3) was the last to come “ into line.” 
Only the hinder angle of the enamelled trenchant border of the crown of this tooth 
is touched, whilst the dentine is exposed on the ridges of the last molar (ib. fig. 2, m 3). 
The crown of d 4 has been worn down nearly to the bases of the two lobes, and the 
dentine of the mid link connects the two exposed wide tracts of that tissue, forming the 
bases of the worn-out ridges. The next molar (ib. ib. m 1 ) shows a greater degree of 
wear; the dentinal part of the mid link is broader, and the lobes, as seen in the 
side view (ib. fig. 1, m 1 ), are worn down lower or nearer to their base than in d 4. The 
front lobe of m 2 has been abraded to the level of the link, which, being low in this 
species of Protemnodon , is hardly touched. A broad tract of dentine is also exposed on 
the hind lobe. A narrower bilobed tract appears on the front lobe of m 3 ; the 
enamelled summit of the hind lobe is smoothly worn downward and backward. 
The prebasal ridge (f) is broadest in this tooth, and shows a low link (s) continued 
* Philosophical Transactions, 1871, p. 250, fig. 18. + Ibid. fig. 16. 
4 : Proceedings of the Geological Society of London, vol. xv. p. 185 (June 23, 1858). 
