PROFESSOR OWEN ON THE FOSSIL MAMMALS .#0F AUSTRALIA. 
549 
the articular end of the bone (ib. a , c ) the base of the triangle, which is elongate and 
irregular. 
The articular or glenoid cavity (ib. d ) presents the usual oval shape with the small 
end upward (ib. fig. 3) ; the concavity is deepest lengthwise, and the apical part is most 
produced. The outer border beneath the acromion (e) has been broken off, indicative 
of its prominence, which is better preserved in the articular cavity of the fragment of 
the right scapula, showing its resemblance to that part in Macropus. This border 
subsides, becoming thick and convex as it approaches the small or coracoid end of the 
cavity. The lower border is continued into 
a rugged triangular surface beneath (fig. 3, a) 
for the attachment of the long head of the 
triceps; the upper apical part is produced, 
beak-like, beyond the base of the coracoid 
(c). The inner margin is low near the apex, 
but less obtuse than the corresponding part 
of the outer one ; it is more produced as it 
descends ; but this margin subsides gradually 
into the subscapular one. 
The spine (ib. fig. 1 , f) begins by a gradual 
elevation of the lower or hinder half of the 
hinder surface of the “base”(&), which ele- 
vation contracts as it rises from that surface 
to a thickness of 1^ inch. The free border, 
of this thickness, is also flat ; the spine gra- 
dually rising as it advances, describes a 
slight curve toward the upper or anterior 
costa (g) ; the lower margin of the free border 
becomes most produced, and, as the spine 
expands into the acromion ( e ), this margin 
also expands and becomes rough for muscular 
attachments, and in the present specimen 
forms the most prominent part of the acro- 
mion ; but the end of this process is broken 
off. From a pencil-sketch of this scapula 
made by Sir Thomas Mitchell when it 
arrived at Sydney (Woodcut, fig. 6), the acro- 
, .. , . _ , , , . Scapula of Diprotodon : one-fifth nat. size, 
mion ( e ) continued to expand to an obliquely 
truncate end, having the upper or fore angle most produced, and, as it were, slightly 
twisted towards the coracoid ( c ) (indicated by the dotted line in fig. 1, Plate XLV.). As 
the spine (ib. f ) rises from the scapular plate, it becomes compressed or thinner beneath 
the free margin, and presents a smooth concave surface to each scapular fossa 
Fig. 6. 
