1038 
PROFESSOR OWEN ON SOME REMAINS OF THE 
The following differences, though of minor import, may be noted. The anterior 
(articular concave) surface of the centrum has not the “ shallow transversely lengthened 
pit at the centre the two very shallow depressions at the fore part of the under 
surface are less marked. Better defined is the pair of tubercles above the entry of the 
neural canal (Plate 34, fig. 2, n). The neural spine (ns) is entire : the ridge dividing 
the upper surface of the neural arch is continued into the sharp anterior border of the 
spine ; this abruptly gains breadth towards its hinder part, which is traversed by an 
obtuse medial rising; but this, as it descends, narrows, and is continued below the 
root of the spine into a sharp ridge above the exit of the neural canal, dividing there 
the interspace between the post-zygapophyses, as the anterior ridge (r) does that part 
of the roof of the neural arch. 
The spine (ns) of the vertebra (ib., figs. 1 and 2), which is probably from the middle 
of the back, is 2 inches 6 lines in length anteriorly, 2 inches posteriorly. Here the 
base is broadened by a pair of obtuse ridges continued from the upper part of the 
post-zygapophyses (z) contracting as they rise, and finally subsiding upon the broader 
part of the spine. The antero-posterior diameter of the spine is the same throughout: 
the summit is truncate and is formed by a partially coalesced epiphysis. The extreme 
contraction of the outlets of the neural canal, noted in the former Part,t is more 
striking in the present large vertebra, especially that of the anterior one (ib., fig. 2, n), 
of which the vertical diameter does not exceed 3 lines. 
The chief difference presented by the dorsal vertebrae of Moloch horridus, which for 
reasons subsequently given is here contrasted with corresponding vertebrae of Mega¬ 
lama pnsca, besides that of general size, is the greater relative capacity of the neural 
canal (ib., fig. 4). 
In the sacral vertebrae of Megalania\ (Plate 35, figs. 1 and 2) the neural canal (n) 
is enlarged in relation to the part of the myelon which was connected with the nerves 
of the hinder limbs, and I infer the possession of these in proportions at least equal to 
those in Moloch from this character. Although the vertical diameter of the anterior 
concavity of the centrum is reduced to 1 inch 2 lines, that of the neural canal is 
increased to 5 lines ; and at the opposite end to 6 lines : the transverse diameter of 
each outlet being 11 lines. The sacral centrum gains in breadth, while losing in 
height : the two diameters of the anterior cup (c) are, respectively, 2 inches 4 lines 
and 1 inch 3 lines. The under surface of the centrum (ib., fig. 2) is flattened, with a 
feeble transverse concavity along its medial third. The length of the centrum is 
2 inches 2 lines; the breadth behind the base of the “ transverse process ” is 2 inches 
G lines. This process (p), combining par- and di-apophyses, extends its base over the 
fore half of the coalesced centrum and neural arch. It, probably, extended outward, 
by the addition of a coalesced costal element, to the degree shown in the sacral 
vertebra) of Moloch (ib., fig. 5, d) and most other Land-Lizards; it has been broken 
* Ibid., p. 44. t Loc. cit ., p. 45. 
t Transmitted by F. M. Raynal, Esq., M.R.C.S., from the neighbourhood of Melbourne, Yictoria, 1862. 
