322 



agrees with Phascolomys vombatus and Phase, platyrltimis (Woodcut, fig. 7,b); whilst it 

 differs from Phascolomys latifrons (Woodcut, fig. 8, 5), in which the postpalatal apertures 

 extend forward beyond, or at least as far as, the interval between the last and penulti- 

 mate sockets f. In the more advanced portion of the roof of the mouth I noticed (in 



1 S 15) a character % in Phascolomys latifrons by which it differed from Phase, vombatus, 

 and as I now know it also differs from Phase, platyrhinus. The portion of bony palate 

 between the molary series and the incisors is more concave transversely, or deeper, in 

 Phascolomys latifrons (Woodcut, fig. 8. si', «», », 22), and the channel is bounded by well- 

 defined or sharp borders: this character is much better marked in the fossil (Plate L. 

 fig. 5, si', 2i', 22, 2j) than in the skulls of Phascolomys vombatus or Phase, platyrhinus. 



Another character in which the fossil resembles Phascolomys latifrons more than it 

 does the other two recent species is the greater vertical extent of the maxillary (Plate 

 L. tigs 3 & 4, si*) beneath the origin of the malar or zygomatic process (21*) of that 

 bone (compare with Cuts 5 & 6, >i»). I shall recur to this character in the description 

 of another fossil of the present genus. 



§ 8. Upper molars of Phascolomys Mitchelli, (ho. — The differential characters of these 

 teeth, as compared with their homologues in Phascolomys vombatus, have been elsewhere 

 pointed out §. As to the two larger existing species, in the molar dentition of the upper 

 jaw Phascolomys Mitchell? more resembles the platyrhine than the broad-fronted Wombat. 

 In the latter the right and left upper molar series (Woodcut, fig. 8, da-ma) run more 

 parallel to each other, are less convergent anteriorly, with absolute greater breadth 

 of the bony palate there. The first molar (d a) in Phascolomys latifrons is, relatively to 

 the second, larger in both upper and under jaws. I therefore limit the comparison of 

 the upper molars in the present fossil to those of Phascolomys platyrhinus (fig. 7, d a-m a). 

 The extent of the five alveoli, lengthwise, taken at their outlets, is the same in both ; 

 or at least the fossil (Plate L. fig. 5, d a-m a) exceeds only by about a line, giving 



2 inches 2| lines instead of 2 inches 1 line as in Phascolomys platyrhinus. I have seen 

 no example of Phascolomys latifrons in which the molar series extended beyond 2 inches ; 

 it is commonly less, as in Woodcut, fig. 8. 



The alveolus of the first molar (da) of the fossil indicates a tooth not larger than in 

 the Platyrhine Wombat. The other four molars, of which the first three are preserved 

 on the left side and the last two on the right side, closely repeat the characters of these 

 teeth in the Platyrhine Wombat ||. This gives more weight to the differential characters 

 of greater length and less breadth of the nasals, the greater concavity and sharper defi- 



t In the latter variety (fig. 8) the apertures should extend more forward than is represented, 

 i Trans. Zool. Soc. vol. ii. plate lxxi. fig. 1. "The palatal surface of the intermaxillaries is deeper" 

 (p. 304). 



§ Mitchell's ' Three Expeditions into the Interior of Eastern Australia,' vol. ii. p. 3G8, pi. 48. See also 

 Watebhotjsb, ' Natural History of the Mammalia,' 8vo, 1845, p. 244. 



|| The second molar is abnormally worn, through slight displacement of the opposing tooth, as happens in 

 other partially enamelled teeth of perpetual growth. 



