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its anteroposterior extent would be about 2 inches 8 lines ; and this is the extent shown 

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

 colomys 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. 



The margin of the diastemal part of the upper jaw (Plate LVII. fig. 2, I) 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 very short way down upon the inner side or large end of the oval ; it arches 

 down 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 

 Phascolomys 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 Phascolomys medius the malar process of the maxillary (Plate LVII. fig. 3, 21*) 

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

 maxillary is moderately concave vertically ; in the smaller living Wombats 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 LX. fig. 7) shows a close 

 correspondence with the fossil in this character. 



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

 length resembles that in Phascolomys latifrons ; in Phase, platyrhinus 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 Phase, medius contracts transversely, seemingly more 

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

 maxillo-premaxillary 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 LVII. figs. 3, 4, & 5, 22, 22) are relatively higher or deeper than in Phas- 

 colomys latifrons, in which they are relatively higher than in the bare-nosed Wombats. 

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



The photograph above referred to (Plate LX. 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 LVII. fig. 2) from Eton Vale. 



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

 Phascolomys 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 

 the teeth alone of the present fossil, that a still larger Wombat than the platyrhine 

 continental species had formerly existed in both Queensland and New South Wales. 



As so much, however, depends on ascertained constancy of characters in the compa- 

 rative work preliminary to determination of extinct species, I believe it will be acceptable 



32* 



