PKOFESSOE OWEX OX THE FOSSIL MAMMALS OF AUSTEALIA. 



243 



position to the hind lobe of m i. 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 PJiascolomys latifrons, 

 its antero-posterior extent would be about 2 inches 8 lines ; and this is the extent shown 

 in a photograph (Plate XXXV. fig. 7), nat. size, of a portion of the upper jaw of Phas- 

 colomijs medius, with the entire molar series of the right side, from the breccia-cave of 

 Wellington Valley, New South Wales, in the Australian Museum, Sydney, for which I 

 am indebted to the Trustees of that Museum and their able Curator, Mr. Kkefft. 



The margin of the diastemal part of the upper jaw (Plate XXXII. fig. 2, /) is sharp 

 to near the incisive outlets (i), where it broadens and becomes obtuse. The cross section 

 of the incisor (ib. fig. 6) is a transverse oval, 6 lines in long diameter, 4^ lines in short 

 diameter ; the small end of the oval is obtuse and turned outward. The enamel bends 

 from above a veiy short way down upon the inner side or large end of the oval ; it arches 

 do^vn over the small end. The enamelled surface of the tooth is more convex than 

 the hind or lower cement-clad surface ; but this is more convex, or less flattened, than in 

 PJiascolomys latifrons. The long and short diameters of the transverse section of the 

 incisor in the other two living species are in opposite directions to those in the present 

 fossil and the Latifront Wombat. 



In PJiascolomys medius the malar process of the maxillary (Plate XXXII. fig. 3, 2i») 

 rises thirteen lines above the alveolus of the third molar: the intervening wall of the 

 maxillary is moderately concave vertically ; in the smaller living '\A'ombats it is convex ; 

 but in the character of height of origin of the process we again have an evidence of 

 affinity to the latifront species. The photograph (Plate XXXV. fig. 7) shows a close 

 correspondence with the fossil in this character. 



The prezygomatic ridge (Plate XXXII. fig. 3, m) is low and broad, but in course and 

 length resembles that in PJiascolomys latifrons ; in PJiasc.i)latyrJiinus this ridge is shorter, 

 relatively thicker, and more prominent. Anterior to the ridge and the socket of d 3 the 

 maxillary part of the skull of PJiasc. medius contracts transversely, seemingly more 

 ^ suddenly than in existing Wombats, to form the diastemal part of the upper jaw. The 

 maxillo-premaxiUary suture runs vertically, with a sinuous and strongly denticulate 

 course, about 5 lines in advance of the socket of d 3. The front walls of the incisive 

 sockets (Plate XXXII. figs. 3, 4, & 5, 22, 22) are relatively higher or deeper than in PJias- 

 colomys latifrons, in which they are relatively higher than in the bare-nosed A^'ombats. 

 The contour of this part of the prem axillary is rather concave in the fossil. 



The photograph above referred to (Plate XXXV. fig. 7) of the cave fossil shows the 

 same depth and shape of the bony palate, and the same somewhat abrupt contraction 

 of the diastemal part of the maxillary, as in the fossil (Plate XXXII. fig. 2) from 

 Eton Vale. 



These evidences of specific distinction, superadded to the marked superiority of size of 

 PJiascolomys medius, are acceptable ; although the degree of constancy of size and shape 

 of teeth in the three species of living Wombats would have justified an inference, from 



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