324 



the molar alveoli, fractured at both ends (Plate L. figs. 7, 8) ; the anterior fracture 

 exposes the socket of the first molar, d a. By the anterior contraction of the palate and 

 by the size and proportions of the alveoli the fossil resembles Phascolomys j^tyrhinus; 

 by the parallelism transverely of the fore part of the postpalatal aperture and the same 

 part of the posterior alveolus, and by the height of the maxillary below the malar process 

 of that bone (fig. 7, »•), it resembles Phascolomys latifrons. By the combination of both 

 characters it proves its relationship to Phascolomys Mitchelli ; as in that species the prezy- 

 gomatic ridge is less prominent or definite, and is higher placed than in existing Wombats. 



§ 10. Palate and upper molars, Phascolomys Mitchelli, from freshwater deposits, 

 Queensland. — In a heavy petrified fragment of skull (Plate LI. figs. 1-4) f, including 

 the molary series, upper jaw, and their alveoli, with the bony palate from its hind border 

 or bar (a) to 4 lines in advance of the molars (21, 21), the palate, as compared with that 

 of the last-described fossil (Plate L. fig. 5), is more concave transversely, and its 

 concavity is divided by a sharp ridge, extending from the interpalatine (20, 20) along the 

 intermaxillary J palatal suture, as far forward as the second molar {d*). 



The upper molars have a somewhat zigzag arrangement: the second (Plate LI. 

 fig. 1, d 4) extends more mesiad than the first (d 3) or the third (»i 1), the hind lobe of 

 the third more so than the fore lobe of the fourth (m 2), and the hind lobe of the fourth 

 more so than the fore lobe of the last molar (m 3). This arrangement is also shown in 

 the palatal view of the fossil of Phascolomys Mitchelli (Plate L. fig. 5), and by the 

 alveoli in the more fragmentary fossil of the same species (fig. 8) of the same Plate. 

 The same character is seen in a minor degree in the outer contour of the grinding- 

 surfaces. The antcro-external angle of one tooth projects more outwardly than the 

 poster o-external angle of the tooth in advance. This arrangement, a tendency to which 

 has been noted in Diprotodon and Nototherium, is more marked in the Tasmanian and 

 Platyrhine Wombats, as in Mitchell's fossil, than in Phascolomys latifrons. 



The intermolary bony palate in the present fossil (Plate LI. fig. 1), though 

 exceeding in length by the antero-posterior diameter of the last molar tooth that of 

 Phascolomys latifrons (Woodcut, fig. 8), is narrower anteriorly than in that species, 

 without being so broad posteriorly. It further differs from both this, the Platyrhine 

 (Woodcut, fig. 7) and the Tasmanian existing Wombats, in the smaller size of the post- 

 palatal foramina (ib. b, b) ; they are absolutely smaller than in Phascolomys vombatus, 

 although the fossil indicates an animal as large as the largest Phascolomys platyrhinus. 

 These foramina are, unfortunately, not preserved in the two previously described fossils ; 

 but the anterior boundaries in the subject of fig. 5, Plate L., indicate a size or breadth 

 of the foramina equal to those in either the Latifront or Platyrhine existing species. 



The antero-posterior extent of the molary alveoli, upper jaw, of the present fossil is 



f This fossil was presented to the British Museum, in 1861, by George Bexxett, Esq., F.L.S. It is from a 

 freshwater deposit, Darling Downs. 



X I use the term to signify the suture between the maxillary bones, in a sense different from that in which 

 it is sometimes applied, viz. to the " premaxillary bone." 



