340 



species (ib. fig. 1, /, a*, ?). The same relationship is shown in the form of the intcrmolar 

 part of the bony palate, which is less contracted anteriorly in the fossil than in the 

 bare-nosed Wombats {Phascolomys plafyrhhuis, Plate LVIII. 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 LVII. fig. 2, a, a). This deeply arched form of the bony roof of 

 the month will be again noted in larger extinct species of Wombat. 



The present appears to have been one half larger than the largest individuals of 

 I'IhisiuiIiiiiijjs 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 LVIII. fig. 1, 2i', 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 LVII. 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 forward. 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, vombatus. 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 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 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 

 LVII. 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, m 1) resembles d 4 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 

 position to the hind lobe of m 1. The enamel in all the molars is longitudinally striate, 

 the striae being feebly marked and subrugose. 



Completing the upper molar series according to the analogy of Phascolomys latifrons, 



