RECORDS OF W.A. MUSEUM. 
[21 
sign of any anchylosis either at the centrum or at the outer 
extremities of the transverse processes. On the other hand, an 
examination of the outer margin of the right diapophysis, which is 
practically intact, reveals that there was undoubted articulation 
with the ilium. 
The sacrum was recovered from the deposit and luckily has 
suffered little from the process of separating the bone from the 
matrix, only the left diapophysis of the fourth sacral being absent. 
Prof. Oweni considered that the form adopted by the fused 
diapophysis was distinct in the different species, and his figures 
certainly show considerable variation, but later Prof. McCoy states^ 
“ The vertebral bones forming the sacrum are singularly diverse in 
each of the living species of Wombat or Phascolomys, and were 
supposed to afford good specific characters, but I find the variations 
of individuals of each species so great that I attach no value to 
characters which, without this experience might seem specific.” 
This view is confirmed by our specimen which has singular 
resemblances to both the platyvhiiius and latifroiis types, its 
description is as follows : — Sacrum consisting of four anchylosed 
vertebra;, the posterior moiety of the first centum considerably 
narrower than the anterior, which has the same width as the 
centrum of the fourth lumbar ; the posterior portion of the centrum 
of the first sacral, the second, third, and fourth are all equal in 
width but losing considerably in height as we proceed towards the 
caudals. Height of the neural spine on the first vertebra about 
2mm,, the spine is scarcely visible on the second and entirely 
absent on the third and fourth, the articular processes well 
developed on the anterior aspect of the first sacral, but fused and 
more and more indistinct and rudimentary as they approach the 
last sacral, the posterior face of which has more perfect processes 
for the articulation of the first caudal. The diapophysis, all 
anchylosed at their distal ends, the first and anterior moiety of the 
second articulating with the ilium on either side. The diapophysis 
of the third and fourth considerably broader but much thinner than 
those of the second, which again have not one-eighth the volume 
of those belonging to the first. The vacuities between the first 
1 Owen, Trans. Zool. Soc., vol. 8, p. 468-g, Ext. Mam. Aust., p. 359, et seq. 
2 McCoy, loc. cit., p. 27. 
