304 PROFESSOR OWEN ON THE SPECIES OF PHASCOLOMYS. 
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 Ph. latifrons. But it differs, as do the other mandibles of the same species, 
as well as those of Ph. vombatus (ib. fig. 2, 7,s), in the larger, especially broader incisive 
alveoli, and the oblique course of their upper margins from the mid line of the sym- 
physis outward and backward. ‘The fore end of the symphysis of Ph. latifrons is at 
once recognizable by the narrower outlets of the incisive alveoli, and the more trans- 
verse course of their upper border (Pl. LVII. fig. 3). The lateral borders of the outlets 
are also more nearly vertical (Pl. LIV. fig. 3, s'), and do not slope backward as they 
descend, like those of the incisor alveolar outlets in Ph. platyrhinus (ib. fig. 2) and Ph. 
vombatus (ib. fig. 1)*. 
With the narrower alveoli associated with the more compressed form of the incisors 
of Ph. latifrons one may predicate a generally narrower diastemal part of the sym- 
physis, the upper surface of which, with a median 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 (Pl. LVII. fig. 3, 7, s'). In one jaw of Ph. 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 ante- 
rior outlet (v) of the dental canal, in three mandibles of Ph. platyrhinus (Pl. LIV. fig. 2), 
is 1 inch 4 lines, or 1 inch 5 lines, behind the foremost point of the symphysis. In 
one mandible of Ph. latifrons (ib. fig. 3) it is 1 inch behind the fore end of the sym- 
physis; 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’. I may further note 
that, in the mandibles of two individuals, examined since describing that of the type 
skull of Ph. latifrons, the intercommunicating foramen from the entry of the dental 
canal to the outer surface of the base of the coronoid is smaller in one (PI. LV. fig. 4, p), 
as in the type mandible, than in the platyrhine and Tasmanian Wombats; while in 
another mandible of Ph. latifrons it did not exist. It is interesting to find this variety, 
because, in the great Diprotodon and Notothere, 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, and this supports Dr. Murie’s view of the hairy-nosed Wombat. 
The mandible of the Tasmanian Wombat has the singular proportions of being as 
broad as it is long. In the specimen figured (Pl. LIV. fig. 1) the length is 4 inches 
6 lines. In one jaw of Ph. platyrhinus the length is 6 inches, the breadth 5 inches 
. This latter character, differentiating Phascolomys vombatus from Ph. latifrons, is shown in figs. 3, ¢ & 7 ¢ of 
pl. xxxyii. tom. cit. 
2 This character is shown in the figures of the mandible of the Tasmanian and continental broad-fronted 
Wombats in pl. xxxvii. of my “Second Memoir” (tom. cit.). But I could not then, as now, depend upon the 
constancy of such character, in which the platyrhine continental Wombat, as usual, resembles the Tasmanian 
species. 
