[ 173 J 
IX. On the Fossil Mammals of Australia. — Part VI. Genus Phascolomys, Geoffk. 
By Professor Owen, F.JR.S. &c. 
Received September 14, — Read 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 skulP’f. 
In the 4 Descriptive Catalogue of the Osteological Series in the Museum of the 
Royal 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 vombatus,” was also noted 
among the characters differentiating a third species of existing Wombat defined in that 
work J as Phascolomys platyrhinus. 
§ 2. Nasal bones 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 (;s) 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 (iy) extend forward 
* Transactions of the Zoological Society, vol. ii. (1838) p. 387. 
t lb. vol. iii. (1845) p. 304, pi. xxxvii. figs. 1 & 4. 
t 4to (1853), p. 334. 
§ This proportion is expressed as follows by Dr. Murie 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 
