242 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
In the relative length of the interval between the socket of the incisor (Plate XXXII. 
fig. 2, i) and that of the anterior molar (d 3 ), the present fossil resembles the latifront 
species (ib. fig. 1, l. 22', i). The same relationship is shown in the form of the intermolar 
part of the bony palate, which is less contracted anteriorly in the fossil than in the 
bare-nosed Wombats (Phascolomys platyrhinus, Plate XXXIII. fig. 1*). The entire 
bony palate is more concave transversely in the hairy-nosed Wombat than in the other 
recent kinds ; and this character is more strongly marked in the fossil, especially in the 
depth of the diastemal palatal tract into which open the “incisive” or premaxillo- 
maxiilary palatal foramina (Plate XXXII. fig. 2, a, a). This deeply arched form of the 
bony roof of the mouth will be again noted in larger extinct species of Wombat. 
The present appears to have been one half larger than the largest individuals of 
Phascolomys platyrhinus. I 11 a specimen of this existing species, the length of the 
diastema equals three fifteenths of that of the entire skull, which is 7 inches 5 lines 
(Plate XXXIII. fig. 1, 21', 22'). If the diastema bore the same proportion in Phascolomys 
medius , the length of its skull may be set down at 1 foot 6 inches. 
The first molar (Plate XXXII. fig. 2, d 3), with the usual curvature, concave outward, 
and with the exposed part inclined obliquely backward, has a grinding-surface, or trans- 
verse section, of an oval form, with the small end forwards. The long diameter is 
5 lines, and is in the direction of the molar series ; the greatest transverse diameter is 
4 lines. The enamel does not extend from the inner surface so far outward upon 
either the front or back parts of the tooth as in the recent Wombats; it shows no 
trace of the antero-internal fold which is feebly marked in Phascolomys latifrons , and 
strongly marked in Phascolomys platyrhinus and Phase, vombcitus. The coat of cement 
covering the outer side of the tooth is continued in a thinner layer over part of the 
enamel, and where absent has been probably accidentally removed from that partial 
deposit of the hardest dental tissue. 
The second molar (ib. d 4) is divided by the usual deep inner groove and shallow 
outer one into two lobes, the hinder one being broader both transversely and from 
before backward. The antero-posterior extent of the grinding-surface is 74 lines, the 
transverse extent of the front lobe is 4 lines, of the hind lobe 44 lines ; the inner end of 
this lobe is less obtusely rounded than that of the front lobe. From the unequal depth 
of the outer and inner alveolar walls, only a small part (about a line) of the unenamelled 
outer part of the tooth projects from the socket, while an extent of four lines of the 
inner enamelled part of the tooth projects beyond the lower inner alveolar wall (Plate 
XXXII. fig. 7, d 4). The enamel-coat is thinner at the bottom of the inner inflection or 
groove, and terminates near the rounded external angles of the tooth : portions of the 
thin cement covering the enamel are preserved. 
The third molar (ib. fig. 2, mi ) resembles d * in size and shape; the anterior lobe 
does not extend so far inward as the contiguous lobe of the antecedent molar. The 
portion of the anterior lobe preserved of the fourth molar ( m 2) shows the same relative 
* See also Trans. Zool. Soc. vol. ii. plate lsxi. fig. 6 ( Phascolomys vombatus). 
