250 
PROFESSOR H. G. SEELEY OX THE STRUCTURE, ORGAXIZATIOX, 
vertebrae preserved in natural articulation in the basin forined by the expanded 
scpiamosal bones. 
There is no reason to doubt that in this species the occipital condyle was small, 
and as short as in allied types, though it is not exposed. Attached to it, apparently, 
is a bony mass projecting backward, which is embedded in matrix, except at the 
base, and on part of the right side ; and this I regard as being probably the anchy- 
losed atlas and axis; not that there is any visible evidence of union between the 
bones, but the antero-posterior extent of the ossification is 2'3 centims., while the 
succeeding cervical centrums have an average length of 1'7 centim., and I know of 
no animal in which the atlas is longer than the succeeding vertebree, while a similar 
increased length is found when atlas and axis are anch_)losed. Its posterior articular 
face is less than 2 centims. deep. At its base is a large tubercle, which may be lateral, 
and is probably one of a pair ; though the other, if present, is hidden by matrix. 
The heisrht from this tubercle to the summit of the neural arch is 4 centims. The 
o 
neural arch, which is imperfectly exposed, extends backward for a centimetre behind 
the articular face of the centrum. The succeeding vertebrae are dislocated, and turned 
round at a right angle. The matrix has been removed so as to expose both the left 
side and the base. 
The first of the free vertebrae has many of the characters of an inter-centrum, for it 
has no neural arch, but the centrum has been partly chiselled away on the under side. 
Its antero-posterior extent, as preserved, is 1'7 centim., and, therefore, as long as the 
vertebrae which follow it. On its left upper anterior angle is a large ovate articular 
facet, slightly elevated, with a sharp border ; it looks forward and outward ; and I 
can only suppose that the neural arch of the axis may have rested upon it. The 
surface beneath it is deeply excavated. The neural arch of the following vertebra is 
in close contact with the superior paid of its jjosterior border, and the neural spine of 
that vertebra extends forward, so that it must have been in contact with the neural 
spine of the axis. This affords, so far as I am aware, the first evidence of an inter- 
centrum among true Reptilia developed to the size of an ordinary centrum, as in 
Diplovertehroii. There are no interspaces between the vertebree ; their neural arches 
interlock slightly, and the centrums are in close contact. 
The next vertebra has the centrum 1‘7 or 1’8 centim. long, flattened on the under 
side in front, but forming a median ridge behind. At the sides of this flattened part 
of the base is a pair of tubercles, moderately elevated, placed obliquely so as to look 
backward and upward ; that on the right side is 6 millims. long. The side of the 
centrum is flattened, but slightly concave, inclined a little outward. It has no elevated 
anterior border, as though it were the vertebra to which the inter-centrum belongs. 
The vertical depth of the side of the centrum below the neuro-central suture is about 
1'5 centim. The neural arch is large. It extends transversely beyond the centrum, 
and develops a strong diapophysis directed backward and outward. This process is 
fractured, and only its base is seen, convex above and flattened below ; but it was 
