45 
A &IGAI^TIC LAND-LIZAED FEOM AUSTEALIA. 
The fracture which has broken away the right posterior zygapophysis extends a little 
to the left of the median line, and there may, therefore, have been a neural spine from the 
posterior third of the arch ; but it must have been thin, and was probably, if it existed, 
low; it is represented along the rest of the arch by the ridge {ns) above mentioned, 
which nowhere rises above two lines in height. Thus the breadth of the neural arch 
exceeds its length, and much exceeds its height. 
The extreme contraction of the neural canal {ih. fig. 4, n) forms a striking feature in 
this vertebra, especially in regard to the vertical diameter of the anterior outlet : in the 
posterior outlet this diameter is the longest. The anterior outlet is unsymmetrical, the 
right nerve or vessel from the chord indenting more deeply the vertebra, as it leaves the 
canal. The posterior outlet shows the inward projection of a ridge from the middle of 
each side of the canal ; external to this outlet a low ridge rises vertically from the margin 
of the articular hall to the lower end of the surface of the zygapophysis. 
The free sm-face of the vertebra is in general smooth, or with shallow linear markings 
and impressions, as above described. 
This vertebra belongs to the dorsal series. 
The second vertebra (Plate VIII. figs. 1 & 2), which is somewhat smaller, appears, by 
the greater extent of the costal tubercle (fig. 1, d), and by the longitudinal depression on 
each side of the mid-part of the under surface, to have come from the cervical region. 
The left side of this vertebra was so much mutilated that I had it ground down to a 
flat surface, such as would have been left by a vertical longitudinal section of the bone. 
This exposed the shape of the neural canal (fig. 2, w), which, from its shallow anterior 
outlet (ib. a), deepens to the middle of the vertebra, by the sinking of the floor of the 
canal into the substance of the centrum, whence it contracts a little towards the posterior 
outlet. The ridge indicated at the side of the canal in the preceding vertebra is here 
seen to commence anteriorly from the upper part of the canal, and describing a curve 
similar to, but not quite parallel vrith, that of the floor, to terminate behind near the 
middle of the canal. The large vascular canals and coarse cancellous texture of the sub- 
stance of both the centrum and the neural arch are also shown by this section. There 
was no neural spine on this vertebra, but only the low median ridge corresponding to, 
but less developed than, that partially shown in the foregoing vertebra. 
The subtriangular surface formed by the small shallow impressions in curvilinear lines 
is also present on each side of the fore-part of the median ridge of the neural arch in this 
vertebra, anterior to which is a tubercular rudiment of a ‘ zygosphene *. 
The costal tubercle {ih, fig. I, d) commences about three lines from the lateral border 
of the anterior cup c, and extends to near the anterior zygapophysis, The length ot 
the tubercle is 2 inches 3 lines ; its greatest breadth is 9 lines. 
The shape and aspects of the articular surfaces, both on the centrum and neural arch, 
are the same as in the former vertebra. The general configuration of the vertebrae is 
likewise closely similar. 
* This term is defined in the works cited in the note, p. 46. 
