GIGANTIC LAND-LIZARD FROM AUSTRALIA. 
1039 
away on both sides in the Megalanian specimen described. The post-zygapophyses 
are relatively small and narrow. The medial ridge upon the neural arch rises at once 
to contribute to the neural spine, which accordingly has greater basal breadth than 
in the antecedent vertebrae. This, with other characters, are repeated, in miniature, 
by the sacral vertebrae of Moloch horrid us. 
The caudal vertebrae of Megalania * are represented in my present collection by a 
single specimen (Plate 35, figs. 3 and 4) from about the middle of the tail. In it the 
ordinary proportions of the cup and ball are resumed, with minor flattening of the 
centrum : but the terminal articular surfaces are less oblique, the lower border of the 
cup (c) being more produced and the corresponding part of the ball (h) encroaching 
more upon the under surface of the centrum. The transverse process (d) springs from 
the side of the vertebra further and more distinctly from the pre-zygapophysis (z) 
than in the trunk-vertebrae : with the spinous process it is broken away, but is 
depressed in shape as far as preserved. A pair of hypapophyses (ib., fig. 4, h) rise, 
with an interspace of 3 lines, from the under surface of the centrum, near the ball ( b ) : 
a smooth surface on one of them indicates the haemal arch and spine to have been 
movably articulated, not anchylosed as in Moloch (ib., fig. 6, hs ), to these processes. 
The length of the centrum of the described vertebra of Megalania is 2 inches 1 line ; 
the breadth of the neural arch is 2 inches 8 lines. 
The occipital segment of the skull of Megalania (Plate 36, figs. I and 2,)t shows, 
as in most mature Lizards, confluence of its constituent parts or “ elements.” 
The centrum (“ basioccipital,” ib., fig. 1, i) convex posteriorly, as in the following 
vertebrae, forms the lower half of the occipital condyle, the upper portions being con¬ 
tributed by the bases of the neurapophyses (“ exoccipitals,” ib., 1, - 2 ). The originad 
sutures between these and the centrum are indicated by slight linear depressions. 
The condyle is crescentic in shape and projects wholly behind or beyond the neural 
arch; the upper surface of the centrum in advance of the condyle shows a transverse 
excavation. The breadth of the condyle is 1 inch 9 fines; the medial depth is 9 lines. 
The neural canal (“foramen magnum,” ib., n), the side walls of which are due to the 
exoccipitals, (2/ 2'), is completed in its upper third by the base of the neural spine 
(superoccipital, ib., 3) ; slight linear impressions indicate the original junctions of the 
latter with the exoccipitals. The outlet of the neural or cerebral canal ( n ) is 
subcircular, 1 inch 3 lines in diameter, but as it advances it contracts to a diameter 
of 1 inch, and this is encroached upon by the lateral ridges (ib., fig. 2, n). 
About three inches extent of the base of the skull is preserved in advance of the 
occipital condyle ; it is formed by the coalesced basioccipital and basisphenoid. The 
basioccipital curves down at its mid-part and extends laterally, with a similar curve, 
to form the parapophyses which, beyond the outlets of the vagal nerves, coalesce with 
* Collected by M. St. Jean, at Gowrie, near Drayton, Darling Downs, Queensland, 1866; presented by 
Sir Daniel Cooper, Bart., K.C.M.G. 
f From the same locality as the “ caudal vertebra,” and received at the same date. 
