PROFESSOR OWEN ON THE EOSSIL MAMMALS OP AUSTRALIA. 
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unequal convex tracts by two oblique grooves, of which the hinder one extends nearest 
to the base or root of the tooth ; in the other type (ib. fig. 3) a deeper oblique fissure 
subequally bisects the crown ; it marks off a more prominent fore part of the outer 
surface from a lower and vertically shorter, but rather more longitudinally extended, 
hind traet. As the first of these patterns is repeated in the third upper incisor of 
Kangaroos with a small premolar (Macropus major*), and the second pattern is found 
in Kangaroos with a large trenchant premolar ( Halmaturus ualabatus, II. ruficollis)^ , 
I refer the fossils of the second pattern to Sthenurus Atlas and those of the first pattern 
to Macropus Titan. 
The skull in this extinct species has the triangular form of occiput as in Macropus 
major, the apex of which, forming the summit of the superoccipital ridge, is somewhat 
rounded off. The upper and larger ends of the condyles subside more gradually into 
the occipital surface, and are not defined by a depression there as in Macropus major. 
The channel or concavity between the condyle and paroccipital is relatively wider in 
Macropus Titan. In this species the foramen magnum seems as if it had been notched 
at its upper border, where the exoccipitals may not have met, and where the foramen 
may have been bounded by an intercalated portion of the superoccipital. 
As in Macropus major, also, a second inner ridge from the base of the. paroccipital 
converges towards its fellow as it rises, parallel with the outer ridge, from the mastoid, 
but subsides before attaining the summit of the exterior ridge. 
The crown of the superoccipital arch projects rather more backward in Macr. Titan 
than in Macr. major ; it is not on a vertical plane with that of the occipital foramen, 
nor does it slope, as in many recent Kangaroos, forward from that foramen. The 
surface below the arch is traversed by a less prominent median vertical ridge in 
Macropus Titan than in Macr. major. 
The upper border of the occipital foramen is mutilated in the fossil, but seems to 
have been more arched, less regular, than in Macr. major. 
The basioccipital (Plate 26. fig. 1, i) is carinate below, as in Macr. major $ ; but there 
is more tumefaction at its suture with the basisphenoid in Macr. Titan. 
A low crest runs along the line of the sagittal suture in the fossil, which bifurcates 
anteriorly, the divisions diverging to the postorbital prominences, which, as usual in the 
genus, are feeble. In Macropus rufus, at a similar phase of dentition with the fossil, 
the sigittal suture persists, and the low ridges bounding above the crotaphyte surfaces 
have not met at the mid line. 
The fore part of the glenoid surface for the mandibular joint, An Macropus Titan, is 
contributed by the malar as in other Kangaroos. The outer surface of the zygoma 
seems not to have been so deeply impressed or concave as in Macropus major and Macr. 
rufus. The facial part of the skull anterior to the orbits is relatively broader in Macr. 
Titan than in either of the above-named existing species. The antorbital foramen is 
* Tom. cit. plate xx. fig. 17. t Hid- figs. 20, 21. 
* Also as in Macropus rufus-. see “Osteol. of Marsupialia. — Part Y.,” Zool. Trans, vol. ix. pi. lxxiy. fig. 3. 
