PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
187 
physis outward and backward. The fore end of the symphysis of Phase, latifrons is at 
once recognizable by the narrower outlets of the incisive alveoli, and the more transverse 
course of their upper border (Plate XX. tig. 1, s'). The lateral borders of the outlets 
are also more nearly vertical, and do not slope backward as they descend, like those of 
the incisive alveolar outlets in Phascolomys platyrhinus and Phase, vombatus *. 
With the narrower alveoli associated with the more compressed form of the incisors 
of Phase, latifrons, one may predicate of a generally narrower diastemal part of the 
symphysis, the upper surface of which, with a mesial canal towards the end and the two 
parallel longitudinal grooves obsolete or nearly so, is better defined from the sides of 
this part of the symphysis. In one jaw of Phase, latifrons the defining ridges are sharp, 
and the intervening upper surface is concave transversely to near the incisive outlets, 
where the defining ridges subside. I may note that the anterior outlet ( v ) of the dental 
canal in three mandibles of Pliascolomys platyrhinus is 1 inch 4 lines, or 1 inch 5 lines 
behind the foremost point of the symphysis (Plate XXIP fig. 2, v) : in one mandible of 
Phase, latifrons (ib. fig. 3) it is 1 inch behind the fore end of the symphysis, in another 
mandible it is 10 lines from the same part. The foramen is more anteriorly situated in 
the broad-fronted or hairy-nosed species : it opens nearer to the molar series in Phase, 
vombatus (ib. fig. 1 , , u)j\ I may further note that in the mandibles of two individuals 
examined since describing that of the type skull of Phascolomys latifrons, the intercom- 
municating foramen from the entry of the dental canal to the outer surface of the base 
of the coronoid is smaller in one, as in the type mandible, than in the Platyrhine and 
Tasmanian Wombats, while in the other it does not exist. It is interesting to find 
this variety, because, in the great Piprotodon and Not ot here, with some affinities to 
Phascolomys, the absence of the perforation of the base of the coronoid process is the 
rule, as in the Marsupialia generally. 
The first lower molar (d s) in Phase, latifrons (Plate XX. fig. 1) has a sub quadrate 
transverse section ; in Phase, platyrhinus (Plate XIX. fig. 2) and Phase, vombatus (ib. 
fig. 1, d 3 ) it has an elliptic or ellipsoid transverse section. The outer depression (Plate 
XXII., f) of the ramus ascendens, or “ ectocrotaphyte cavity,” is less deep in Phase, 
latifrons (ib. fig. 3), and shallows more gradually forward, than in the bare-nosed recent 
species (ib. figs. 1 & 2) ; the inflected angle («), viewed from below as in Plate XXIII., 
has a broader base in proportion to its length, and is not produced so far or directly 
backward in Phascolomys latifrons (fig. 3) as in Phase, platyrhinus (fig. 1). 
§ 12 . Mandibular characters of extinct Wombats similar in size to the recent species. 
— I now proceed to apply the above characters and comparisons of the mandibles of the 
known existing kinds of Wombat in the attempt to elucidate the fossil mandibular 
* This latter character differentiating Pliascolomys vombatus from Phase, latifrons is shown in figs. 3 c & 7 c 
of plate xxxvii. tom. cit. 
t This character is shown in the figures of the mandible of the Tasmanian and Broad-fronted Wombats in 
plate xxxvii. of my second memoir (tom, cit.) ; but I could hot then, as now, depend upon the constancy of 
such character. 
