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example of d 3 in the remains of large Wombats yet to be described gives 9 lines and 

 4^ lines as the two diameters of its almost elliptical grinding-surface (Plates LXI. 

 & LXII. d 3). Such a tooth cannot have belonged to the same species as the one which 

 has an upper anterior molar with the dimensions above given as characteristic of Phas- 

 colomys magnus (Plate LX. d 3). 



Of this species the lower jaw and teeth have not yet come under my observation. All 

 the examples of the large extinct Wombats now before me for description belong to 

 the species Phascolomys gigas, of which the grinding-surface of a lower molar is figured 

 in the " Article " quoted above, and in my 'Palaeontology' (p. 431, fig. 172, 2nd ed. 1861); 

 the former existence of which Wombat I noticed, some years before, in my second 

 memoir "On the Osteology of the Marsupialia"*. 



Satisfactory evidence of this species has since reached me, of which I propose, first, to 

 describe a considerable proportion of the mandible, obtained by Edward S. Hill, Esq., 

 from a freshwater deposit at Eton Vale, Darling Downs, in 1863, and presented by 

 Sir Daniel Cooper, Bart., to the British Museum. 



It consists of the right ramus (Plate LXI. fig. 1) with the fore part broken off near 

 the socket of the first molar (d 3), and with some mutilation of the outstanding parts of 

 the ascending ramus ; also of the fore part of the left ramus (ib. fig. 2), with the hind 

 part broken off at the socket of the penultimate molar (m 2). They are both parts of the 

 same mandible, and I have therefore supplied, in the subjects of Plate LXI. fig. 2, Plate 

 LXII. fig. 1, and Plate LXIII. fig. 1, from one ramus what was wanting in the other. 



Eeference to Plate LIL, where the side view is given of the mandible in the three 

 known living species of Phascolomys, will make at once appreciable the character of the 

 present extinct Wombat, in the minor relative antero-posterior extent of the ascending 

 ramus, and its greater relative height before dividing into the condylar (b) and coronoid 

 (c) processes. The intervening notch sinks nearly to the level of the grinding-surface of 

 the molars in the recent and smaller extinct Wombats ; whereas in Phascolomys gigas 

 the common plate (f,g) rises much higher before dividing into b and c (Plate LXI. figs. 

 1 & 2). The fore-and-aft extent of the rising branch at the neck of the condyle equals 

 in extent that of the last four molars in Phascolomys platyrhinus, and rather more in 

 Phascolomys latifrons ; in Phascolomys gigas the same dimension equals only the last two 

 molars and half of the antepenultimate one. 



The ectocrotaphyte ridge (Plate LXI. fig. 1, h, h) is relatively more prominent and 

 the depression (f) which it circumscribes below is relatively deeper in Phascolomys gigas 

 than in either the Platyrhine or Tasmanian Wombats, and the intercommunicating 

 vacuity is relatively wider in the gigantic Wombat, in which its long diameter is 9 lines. 



* Trans. Zool. Soc. vol. iii. p. 306, 1845 : — " I have recently obtained evidence from the postpliocene deposits 

 of the district of Melbourne, through the kindness of my friend Dr. Hobson, of an extinct Wombat, or true 

 Phascolomys, at least four times as large as either of the known existing species." These were Phascolomys 

 vombatus and Phascolomys latifrons; the somewhat larger continental Wombat (Phascolomys platyrhinus) had 

 not then been determined. 



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