22 ] 
records of w.a. museum. 
and second pair of diapophysis have their longest axes at right 
angles to the vertebral column, whilst the two succeeding pairs 
have them directed anteriorly, in this way appreciably resembling' 
P. latifrons as figured by Owen 1 . On the other hand, the form under 
discussion differs from both the typical examples as figured by 
Prof. R. Owen in the slight backward extension of the articular 
surfaces for the ilia, but if, as probable, the last lumbar to a great, 
extent assumed the duties of a sacral, then the total extent would, 
closely agree with the area shown in figure 4 of the plate just 
referred to. As a natural consequence of the above peculiarity, 
the width of the sacrum rapidly diminishes at a point one-third' 
down the second vertebra, being considerably earlier than in Owen’s 
example. 
The following measurements are taken : — 
Length of the four sacrals (bodies) 
. . 86 mm. 
Width across diapophysis of Si .. 
.. 72 mm.? 
.. ,, S2 .. 
.. 70 mm. 
S3 .. 
. . 59 mm. 
Width of anterior face of centrum of Si .. 
. . 26 mm. 
,, posterior ,, „ . 
i4imm. 
s 4 . . 
. . 14 mm. 
Greatest height of first sacral, Si 
. . 22 mm. 
.. ,, fourth ,, S4 
. . 12 mm. 
Length of articular surface for ilium 
.. 32 mm.? 
Greatest width of ,, ,, 
. . 19 mm. 
It will be seen from the above that the Mammoth Cave sacrum 
differs from both Owen’s figures in several respects ; it resembles 
both forms, and would be exceedingly difficult to connect 
with either. 
Unfortunately the caudal vertebrae are altogether absent from 
the collection, so that any assistance which they might give is 
missing. There is, however, no doubt that these vertebrae or any 
of them were not united with the sacrals, for the posterior face of 
the last vertebra of the sacrum and the articular processes on the 
degenerated neural arch show that there was no coalescence at 
that point. 
Of the ribs we have very few examples ; the first and second- 
left ribs are practically perfect, but all the others that are 
represented are in a fragmentary condition. 
1 Owen, Ext. Mam. Aust.. pi. xcix., fig. 1. 
