PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
259 
physis (Plate XXVI. fig. 9). It also shows that the comparatively loose union of the 
symphysis had permitted the right ramus to glide a little forward from the left one 
before they were fixed in position by the petrified matrix ; but this correspondence with 
the large living Kangaroos is more decidedly shown in the subject of fig. 11, Plate XXVI. 
The right ramus of fig. 9 includes the last four molars, d i, mi, m 2, m 3, and a part of 
the premolar, p 3 (this tooth, like the crown of m 1 , has suffered more from fracture 
than from masticatory action). The left ramus includes the last three molars and the 
hind half of the crown of d 4. The present fossil was obtained by Henry Hughes, Esq., 
in the freshwater deposits of Queensland, and is now in the Museum of the Natural- 
History Society of Worcester. 
In a fossil with three molar teeth ( d 4, m 1, and m 2), and the formative cavity of m 3, 
these teeth are somewhat inferior in size to their homologues in fig. 13, Plate XXII., 
and probably indicate that they come from the female of Macropus Titan. The sub- 
ject of figs. 12 & 13, Plate XXIII., is the original specimen in the Museum of the 
Royal College of Surgeons, No. 1512*, which first afforded the characters of the 
penultimate and last molars of Macropus Titan : this I now believe to have come from 
a female of that species. 
The mandible of Macropus Titan (Plate XXVI. figs. 11 & 12), after solution of the soft 
parts in its original burial-place, shows the effect of the disturbance of the grave by the 
dislocation of the rami, which had been somewhat loosely attached during life by the 
partial syndesmosis of the symphysis. So separated and shifted, the right ramus being 
pushed about 2 inches in advance of the left, the parts have rested without further 
disturbance long enough to permit the dislocated rami to become connected together by 
the petrified matrix. The bone, which during the same period had undergone some 
degree of petrifaction, appears again to have been subject to movements of the matrix, 
resulting in the amount of fracture of the most prominent parts which is common in 
the fossils from the freshwater beds of the Australian localities yielding the subjects of 
the present paper. But the later disturbances have not affected the artificial union of 
the previously separated and dislocated rami. 
The jaw-bone in this specimen exceeds in depth and a little in length that of the 
Macropus Titan in the Oxford Museum (Plate XXII. figs. 13, 15), but the longitudinal 
extent of the four molars is the same. The present fossil is from an older individual : 
d 4 is worn down to its base, and the ridges of m 3 (both of the lobes and links) show 
more abrasion. The vertically oblong pit toward the inner side of the back part of the 
last molar (ib. fig. 15) is well marked. The symphysial articular surface (ib. fig. 12) is 
neatly defined behind ; its rougher part subsides anteriorly, and ceases about an inch 
from the outlet of the incisive socket. The vertical diameter of this socket is 8 lines ; 
that of the base of the incisor, where the tooth has been broken off, is 7 lines. 
The portion of a left mandibular ramus of a fine old male of Macropus Titan (Plate 
XXVI. fig. 13) shows the largest size of the lower jaw which I have as yet seen in fossils 
* Catalogue, ut supra, p. 325. 
