242 PEOFESSOK OWEX OX THE FOSSIL MAMMALS OF AUSTEALIA. 



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 i), the present fossil resembles the latifront 

 species (ib. fig. 1, I. 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 'platyrMnus^ 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- 

 maxillary 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. In 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 pi'oportion 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, Avith 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 

 cither 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, vombafus. The coat of cement 

 covering the outer side of the tooth is continued in a thinner layer over part of the 

 enamel, and Avhere absent has been probably accidentally removed from that partial 

 deposit of the hardest dental tissue. 



The second molar (ib. d i) 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 7^ lines, the 

 transverse extent of the front lobe is 4 lines, of the hind lobe 4^ 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 uneuamelled 

 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 i). The enamel-coat is thinner at the bottom of the inner inflection or 

 groove, and terminates near the rounded external angles of tlie tootli : portions of the 

 thin cement covering the enamel are preserved. 



The third molar (ib. fig. 2, m \) resembles d* in size and sliape; 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 aUo Trans. ZooL Soc. vol. ii. plate Ixxi. fig. G (rhascolomijs voiiihatus). 



