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IX. On the Fossil Mammals of Australia. — Part VI. Genus Phascolomys^ Gm¥F^. 



By Professor Owen, F.B.S. &c. 



Received September 14, — Eead December 7, 1871. 



§ 1. Introduction. — In a paper "On the Osteology of the Marsupialia" * I noted the 

 expansion of the base of the nasal bones in the genus Phascolomys, and the agreement 

 of the Wombat in this character with the Koala, Phalangers, Petaurists, Myrmeco- 

 bians, Dasyures, and Opossums ; thus indicating, as far as observation then warranted, a 

 general marsupial character of form in those bones. 



In a second paper I entered upon a comparison of the nasal bones in Phascolomys 

 vombatus, Geoff., and Phase, latifrons, Owen, and showed that, in the latter species, 

 " the nasal bones were relatively broader, forming the whole upper surface of the ante- 

 rior third of the skull "f. 



In the ' Descriptive Catalogue of the Osteological Series in the Museum of the 

 Eoyal College of Surgeons of England,' another character was pointed out in " the 

 superior breadth of the part of the maxillary ascending in front of the malar and lacry- 

 mal bones to join the nasals" in Phascolomys latifrons. "The greater relative breadth 

 of the nasal bones, as compared with those of Phascolomys vombatits," was also noted 

 among the characters differentiating a third species of existing Wombat defined in that 

 work J as Ph ascolomys ])latyrhinus. 



§ 2. Nasal hones in Phascolomys vombatus, Per. — I now proceed to consider, as far 

 as materials permit, the amount of variety to which the same species of Wombat may 

 be subject in the nasal bones, — a requisite preliminary to determining the value of these 

 bones in differentiating recent and fossil species of Phascolomys. 



In an old male Tasmanian Wombat [Phase, vombatus) the basal breadth equals two 

 thirds of the length of the pair of nasal bones The outer angles of the nasals, at 

 their base (is), are divided from the lacrymal tubercle (73) by a strip of maxillary (21) 

 4 lines in breadth, joining to that extent the frontal (n). The sides of the pair of nasals 

 converge forward at the hinder third, then run parallel, gently curving inward, and 

 finally gaining the margin of the nostril, with a slight curve outward. Thus the 

 course of each lateral border of the nasals is undulate. Their tips (is') extend forward 



* Transactions of the Zoological Society, vol. ii. (1838) p. 387. 

 t lb. vol. iii. (1845) p. 304, pi. xxxvii. figs. 1 & 4, 

 + 4to (1853), p. 334. 



§ This proportion is expressed as follows by Dr. MuErE in describing his specimen of Phascolomys vombatus : — 

 " The proportional breadth of the two nasal bones at their hinder ends is to their length as 68 to 100." (Proc. 

 Zool. Soc. 1867, p. 802.) 



MDCCCLXXII. 2 A 



