542 
PROFESSOR OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 
In Diprotodon the length of the third cervical centrum is 1 inch 10 lines, the breadth 
of its hind articular surface is 4 inches 3 lines, the height of the vertebra is 8 inches. 
The centrum is without hypapophysis, the vertical extent of the hind surface (Plate 
XLIV. tig. 4, c) is 2 inches 9 lines ; the two extremes of the transverse ellipse are almost 
angular. The base of the parapophysis (ib. and cut, fig. 5,p) extends from near this 
angle forward for 1J inch along the side of the centrum. The upper surface of the 
centrum shows a large medial venous orifice. Both margins of the rising neurapophyses 
are deeply notched for the “ conjugational foramina,” and send off a small diapophysis 
(ib. d) to circumscribe above the vertebrarterial canal. The neural spine (ib. ns), 4 inches 
in height from the roof of the neural canal (ib. n), is compressed from before back- 
ward, simple, obtusely rounded at the end, strengthened by a low medial ridge, both 
before and behind, along its basal half. There is no such development of neural spine 
in the third cervical of Proboscidians ; in the larger herbivorous Marsupials it is as con- 
spicuous as in Diprotodon , but with altered shape ; that in the Wombat most resembling 
the one in Diprotodon, but being relatively lower. 
The fourth cervical (Cut, fig. 5, c 4) much resembles the third ; but, as in the 
Kangaroo, has a shorter spine, resembling, however, in shape that of the third, being 
compressed from before backward instead of from side to side as in Macropus. The slight 
increase of size is in breadth, chiefly of the centrum, not in length or height. The neural 
canal is wider and a little higher ; more space is made for the myelon as it traverses the 
more flexible part of the neck. The large venous foramina and vertical canal are repeated 
on the upper part of the centrum ; the corresponding pair of foramina now also blend 
into a common fossa, as in the Wombat. 
In the fifth cervical (Cut, fig. 5, c 5) the neural spine gains in antero-posterior and 
loses in transverse thickness ; the vertical ridges are 
stronger, especially the one behind ; it appears to 
have been shorter than in the fourth vertebra*. 
The centrum and neural canal have increased, chiefly 
transversely; there is very little increase of length. 
The parapophysis has gained in vertical extent. 
In the series of mutilated vertebrae belonging to 
Mr. Boyd’s specimen of Diprotodon are two dorsals 
(Plate XLIV. figs. 5-8). They show the impres- 
sions for the free articulation of the ribs both before 
and behind (ib. figs. ,pl,pl'), and are remarkable 
for the retention of the short proportion of the cervicals, and for the terminal bifur- 
cation of the antero-posteriorly compressed spine (ib. figs. 5 & 8, ns). They are not con- 
secutive vertebrae, but were not far from one another in the anterior part of the dorsal 
series. 
Fis:. 5. 
A c 4, c 5 
Second to fifth cervical vertebrae, one-sixth 
nat. size; Diprotodon, 
* It is so in the sketch sent me by Sir Thomas Mitchele from Sydney (Cut, fig. 5) ; hut, amongst the 
damages to the specimens in their passage to London, the summit of this spine has been knocked off. 
