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(ib. fig. 1, s) and Platyrhine (ib. fig. 2, s) Wombats. From the fore part of the first 

 molar socket to the back part of the upper division (ib. fig. 6, s*) of the symphysial 

 surface, in the fossil, measures 1 inch ; and this part of the symphysis is on the vertical 

 parallel of the hind lobe of the second molar. The lower division (s) terminates, as in 

 fig. 4, below the interval between d i & m i. 



The fore part of the root of the coronoid, in the fossil (ib. fig. 5, q), stands out from 

 the alveolar wall of the penultimate molar, as in Phase, latifrons ; not from that of the 

 last molar, as is the rule in the Tasmanian (Plate LIT. fig. 1, q) and Platyrhine (ib. fig. 

 2, q) Wombats. The extent of the molar series and the sizes of the individual teeth 

 accord, save in the narrower character of the lower molars, with the teeth of the upper 

 jaw in the subject of figure 5, Plate L. If these fossils are maxillary and mandibular 

 specimens of the same species of Wombat, the lower molars are relatively narrower trans- 

 versely, compared to the upper ones, than in any of the existing species. 



In the mandibular specimen under consideration we see combinations of characters 

 confined severally to distinct species in existing Wombats. I am disposed therefore, 

 and for reasons above assigned, to refer this mandibular fossil, with the maxillary one 

 above cited, to Phascolomys 21itchelli. 



A second similar specimen of left ramus, including part of the symphysis and of the 

 ascending ramus, has a molar series 2 inches in extent, and, as in fig. 5, Plate LIIL, the 

 teeth have the general characters of those in Phascolomys latifrons ; they are trans- 

 versely narrower than in Phascolomys vombatus or Phase, platyrhinus. The ectocrota- 

 phyte depression is deeper than in the perforate mandible of that species ; the perfora- 

 tion (p) here shows a similar position and size. The depth of this fossil jaw at the back 

 part of the symphysis is 1 inch 5 lines. The symphysis terminates below the interval, 

 between the second (d i) and third (m i) molars. The ectalveolar groove is wider than 

 in the subject of fig. 3, Plate LIIL, but is deeper than in the Platyrhine and Tasmanian 

 Wombats. The symphysis is not bilobed behind, as in fig. 6, Plate LV. ; but this and 

 the before-mentioned differences from that subject probably exemplify the range and seat 

 of variety in the mandibular characters of one and the same species. 



The characters noted in the subjects of figs. 4 & 5, Plate LVL, of fig. 4, Plate 

 LV., and of figs. 2 & 3, Plate LIV., are of specific value; but, as in the maxillary 

 fossils (Plate L. figs. 1 & 2), I do not feel grounds for indicating, after comparison of 

 the mandibular fossils from the Wellington- Valley breccia-caves, more than two species 

 of a size not exceeding the known existing W T ombats, and not referable thereto. 



§ 15. Mandibular characters of Phascolomys Thomsoni, Ow. — From the freshwater 

 deposits of Queensland I have received mandibular fossils of the genus Phascolomys, 

 which, with decrease of size, show characters not in accordance with those of any of the 

 cave fossils. 



The subject of figs. 8 & 9, Plate LI., and fig. 7, Plate LV., is a right mandibular 

 ramus, with slight mutilation at both ends. In the lower contour of the jaw, the depth of 

 the ectocrotaphyte depression (/), the breadth of the ectalveolar groove .(%), the position 



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