186 
PROFESSOR OWEX OX THE FOSSIL MAMMALS OF AUSTRALIA. 
suture rises as a longitudinal ridge dividing the bony palate there into two concavities 
or longitudinal channels, leading backward to the postpalatal apertures. 
§ 11. Mandibular characters of existing Wombats. — In differentiating by cranial 
characters the species of Wombat called Phascolomys latifrons , I noted, in comparing 
it with Phascolomys vombatus, that “ the curve of the lower border of the lower jaw is 
much deeper, the inner angle of the condyle is less produced, the coronoid process is 
higher and narrower, and the postsymphysial depression is almost obsolete in the Lati- 
front Wombat”*. With the exception of the latter particular, which is variable in both 
species, subsequently acquired skulls have confirmed the constancy of the above charac- 
ters. They likewise serve to differentiate the mandible of Phase, latifrons from that of 
Phascolomys jjlatyrhinus, except that the coronoid process rises higher in the platyrhine 
species (Plate XXII. fig. 2, c) than in the Tasmanian Wombat (ib. fig. 1, c) ; but the 
broader proportion of the process as compared with that in the Hairy-nosed Wombat 
(ib. fig. 3, c) is retained. The deeper curve described by the lower contour of the jaw 
from the neck of the condyle to the incisive alveoli, as shown in fig. 5, Plate xxxvii. of 
the undercited volumef, is a constant and well-marked character of Phascolomys latifrons ; 
so, likewise, is the less produced inner angle of the condyle, shown in fig. 7, c d, of the 
same Plate. In both the Tasmanian and Platyrhine Wombats this angle is more pro- 
duced and deflected. 
The diastemal part (Plates XIX., XX. & XXI. /, s') of the long symphysis (ib. s, s') is 
subject to some variety in existing Wombats. In two mandibles of Phascolomys gglaty- 
rdiinus , in which the length of the series of molar alveoli is 2 inches 3 lines, that of the 
interval between the first alveolus and the foremost angle of the symphysis is, in one 
skull, 1 inch 7^ lines (Plate XXI. fig. 2), in the other 1 inch 6| lines; the breadth of 
the diastema, midway, is the same in both, viz. 10 lines. 
In a mandible of Phascolomys latifrons with the molar series of alveoli 2 inches in 
extent (Plate XX. fig. 1), the diastema (l, s'), taken as above to the foremost point at 
the interspace of the incisors, is 1 inch 6 lines ; in a second mandible with the molar 
alveoli 1 inch 10^- lines in extent, that of the diastema is also 1 inch 6 lines : the breadth 
of the diastema, midway, is in the first mandible 8 lines, in the second 7 lines. 
In the two mandibles of the Platyrhine Wombat compared, the diastema is slightly 
convex both lengthwise and across ; it is traversed by a pair of shallow^ longitudinal 
grooves, and is not sharply defined from the sides of the symphysis. In a third mandible of 
the same species (Plate XIX. fig. 2, l, l) the defining ridges are better marked, the trans- 
verse convexity is less so ; and this part of the symphysis is rather longer and narrower 
than in the other two mandibles. In these respects the third mandible approaches 
nearer to Phascolomys latifrons ; but it differs, as do the other mandibles of the same 
species as well as those of Phase, vombatus , in the larger, especially broader, incisive 
alveoli, and in the oblique course of their upper margins from the mid line of the sym- 
* “On the Osteology of the Marsupialia’ 
vol. iii. p. 304, plate xxxvii. figs. 2 & 5. 
(Part II.) (1845), in Transactions of the Zoological Society, 
t Trans. Zool. Soc. vol. iii. 
