190 



PEOFESSOE OWEX OX THE EOSSIL MAMMALS OF AUSIEALIA. 



division of the alveolus of m i. The anterior origin of the coronoid appears to be pro- 

 portionally advanced in the fossil. The outer surfoce of the ramus below the beginning 

 of the ectocrotaphyte ridge slopes more gradually inward and lower down before passing 

 into the broad under surface of the jaw in the fossil (Plate XXII. fig. G). In the 

 recent Wombats the same surface curves, with a stronger and shorter convexity, into the 

 lower border, yet less abruptly in Phase, latifrons (ib. fig. 3, k) than in Phase, jjlaty- 

 rhinus (ib. fig. 2, k). 



The ectalveolar groove is longer, deeper, and narrower in the fossil (Plate XIX. fig. 3, u), 

 owing to the more advanced origin of the coronoid {q) and its greater proximity to the 

 last two alveoli [m 2, m 3) ; this difierential character is still more marked as compared 

 with the Platyrhine species (ib. fig. 2, u). From so much of the entocrotaphyte ridge, 

 or anterior beginning of the infiected angle, as is preserved, the degree of inflection 

 appears to have been less in this fossil (Plate XXIII. fig. 5, a) than in the recent species 

 (ib. figs. 1, 2, 3, a). The surface broadening as it recedes, between the ecto- and ento- 

 crotaphyte ridges, is not only flattened but becomes rather concave in the fossil toward 

 the inner border. 



The two hindmost molars in place (Plate XIX. fig. 3, m 2, m 3) are narrower than 

 those in Phase, latifrons (Plate XX. fig. 1, m 2, m a), as are the anterior molars in the 

 fossil previously described (ib. fig. 2, dz, d To the species represented by the last- 

 cited fossil, I am disposed, from the resemblance of the symphysis to that in the imper- 

 forate variety oi Phase, latifrons, to refer the present fossil. They might be parts of the 

 same mandible, as well as of the same species ; but more complete specimens must con- 

 firm or confute this supposition. It is certain that both fossils show the nearest resem- 

 blance to the mandibular imperforate variety of Phaseolomys latifrons above named, 

 yet with marked difi'erences, in value equalling those interpreted and accepted as 

 specific. The part of the dental canal which courses along the inner side of the molar 

 alveoli and the bottoms of the last two alveoli are exposed by fracture of the thin film 

 of bone originally covering them. 



In reference to the characters of the two portions of fossil mandible above defined, as 

 they plainly justify the inference that they belonged to a species of Phaseolomys as 

 distinct from the three accepted recent species as these differ from one another, each 

 might be indicated by a specific name ; and it may ultimately prove that they do belong 

 to distinct species. 



The same remark applies to both or cither in relation to the maxillary fossil from 

 the same cavern (Plate XVII. figs. 2 & G) which I have referred to a Phaseolomys 

 Krrfftii. 



Considering, however, that the two portions of mandibles combine, like that maxillary 

 one, characters of affinity to Pliuseolomys latifruns with divlerential ones forbidding a 

 reference to that species, it may be, and may be probable even, that they all belong to 

 the same extinct species. I prefer, therefore, to indicate them as pai'ts of a Phaseolomys 

 Krrfftii, and leave to those who may be so fortunate as to obtain evidence to the con- 



