552 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
The humerus in Marsupials is not described in either editions (1805, 1835) of the 
‘Lemons d’Anatomie Comparee.’ But in the ‘ Ossemens Fossiles’ (4to, tom. iv. p. 284) 
Cuvier notes the precaution requisite in the examination of the distal articular surface 
of the humerus in Marsupials on account of its resemblance to that in Carnivora. In 
the posthumous 8vo edition of the ‘ Ossemens Fossiles,’ tom. vii. p. 276, after the gene- 
ralization as to the perforation of the inner condyle in Carnivora , is added : “ ainsi que 
chez les Didelphes et dans tous les animaux a bourse.” So likewise De Blainville 
states that the inner condyle of the humerus is perforated, “ chez tous les Didelphes 
sans exception,” using the term in his peculiar taxonomic sense as equivalent to the 
Marsupialia of other zoologists. I have, however, pointed out exceptions to this rule 
in certain Dasyures ( Dasyurus Maugei ), Phalangers (Ph. CooJcei ), and Petaurists*. 
So much it seemed requisite to premise, because the imperforate condition of the inner 
condyle also characterizes the bone in Diprotodon , differentiating it from the humerus 
in Macropus and Phascolomys , without, however, affecting the marsupiality of the great 
extinct Herbivore. To the description of this bone in Diprotodon I now proceed. 
The humerus (Plate XLYI.) is more nearly straight than in other Marsupials, and 
is remarkable for the feeble development of the ridges for muscular attachments. At 
a glance one sees its relations to the restricted offices of support and locomotion with 
much less subserviency than in the smaller existing Marsupials to more varied applica- 
tions of the fore limb. 
The head of the bone (ib. figs. 1 & 2, a, and fig. 3) rises above the tuberosities (5, c), 
forming a very large proportion of the upper end (fig. 3). It has the usual degree of 
convexity, with a full oval contour, the long axis being transverse, and the smaller end 
next the outer tuberosity ; it overhangs the back part of the shaft at its inner two-thirds 
(fig. 1), but in a less degree than in the Kangaroo. The inner tuberosity (b) is represented 
by a low broad, rough ridge, extending from the inner side along the fore part of the 
periphery of the head to near the small outer end of the articular ball ; here it is inter- 
rupted by a wide but very shallow representative of the “ bicipital groove.” The outer 
tuberosity (c) projects in a greater degree from the outer side of the base of the head. 
The broad, low, rounded angle between the fore and outer sides of the humeral shaft, 
continued from the fore end of the outer tuberosity (fig. 2, c), representing at first the 
outer side of the bicipital groove, descends and assumes rather more of the character of 
a muscular ridge at the mid length of the shaft (fig. 2, d) before subsiding. 
The liomologue (ib. e) of the short external ridge in Macropus here projects as strongly 
from that side of the bone, but on the same transverse parallel with the lower, best deve- 
loped part of the deltoid ridge (d). Consequently the external ridge is relatively lower 
placed than in the Kangaroos ; it is also relatively shorter, lengthwise, and stands out 
more abruptly at its upper part. 
The representative of the deltoid ridge divides the fore part of the shaft unequally, and 
the broader division or tract (fig. 2, f) is internal, the narrower division or tract (ib. g) 
* Osteology of Marsupialia, Joe. cit. p. 400. 
