PROFESSOR OWEN\ OX THE FOSSIL MAMMALS OF AUSTRALIA. 



177 



Outside this, in all Latifront Wombats, the fronto-nasal suture runs straight outward to 

 the lacrymal (73), from which bone it is not separated, as in Fhascolomys plaiyrhinus -dnd 

 Phase, vomhatus^ by the maxillary (21). The extent of the naso-maxillary suture (15-21) 

 equals that of the naso-premaxillary suture (15-22). 



These differences in the connexions of the nasals are more significant of specific 

 distinction than the shape of the bones. The naso-maxillo-premaxillary suture (15-21-22) 

 is very slightly concave outwardly in the Latifront "Wombat ; and the free border of the 

 nasals beyond the suture affects a convex bend toward the apices. 



^ 5. Nasal hones in Phascolomys Mitchelli, Ow. — There would be no doubt in deter- 

 mining Phascolomys latifrons by the naso-maxillo-premaxillary part of the skull, at least 

 as being distinct from the other two known recent species, if even the still more charac- 

 teristic part of the frontal bones was wanting. There might be more difficulty in pro- 

 nouncing as to whether a fore part of the skull belonged to Phascolomys ])latyrhinus or 

 to Phase, vombatus. 



I now proceed to compare such a fragment of a fossil skull of a Wombat on the basis 

 of the characters which comparisons of different individuals of the three well-determined 

 recent species of Phascolomys affords. 



The fragment in question (Plate XVII. figs. 1, 3, 4, 5) includes the nasals (15) with 

 parts of the frontals (n), lacrymals (rs), malars (25), maxillaries (21), premaxillaries (22), 

 and palatines (29). The nasals (is) are of the type of those in Phascolomys vombatus and 

 Phascolomys plafyrhinus; in the proportion of basal breadth to length and the speedy 

 narrowing as they advance they resemble the modification shown in Woodcut, fig. 1, 

 p. 174, in Phase, vombatus. But small as is the extent of the naso-maxillary suture 

 (15-21) in Phase, vombatus (figs. 1 & 2) and Phase. platyrMnus (fig. 3), it is still less in 

 the fossil, the apex only of the basal expanse of each nasal (15) touching the maxillary (21) 

 (Plate XVII. fig. 1) on each side of the skull. The naso-premaxillary suture (ib. 15-22, 22 ) 

 runs along the side borders to within half an inch of the extremities (15), which are 

 obtusely pointed, as in Phascolomys platyrhinus. The suture or lateral border of the 

 nasals describes but two curves, concave at the basal half, convex at the apical one ; 

 slight in both, in Phascolomys Mitchelli. The angle formed by the fronto-nasal suture 

 (11-13) is as in Phase, platyrhinus (fig. 3) ; and an obtuse process, 3 lines broad, of the 

 frontal is wedged into the beginning of the internasal suture. 



Seeing the variations in regard to such frontal wedge, as in the sinuous course of the 

 lateral borders of the nasal, these bones could not differentiate by their form the fossil 

 from the existing continental Wombat {Phase, platyrhinus). The superiority of size is 

 but small in the fossil ; but the difference of connexion, shown in the almost exclusion 

 of the maxillary from junction with the nasal, is a satisfactory distinctive characteristic 

 of this part of the skull of the fossil Wombat under consideration, which I refer to the 

 Phascolomys Mitchelli, Ow.* 



* First defined iu Appendix to Mitchell's 'Three Expeditions into the Interior of Eastern Australia,' vol. ii. 

 8to, 1838, pi. 48. figs. 4-7, p. 368 (^2ud ed.). 



