TERTlAliT VEKTEERATA OF THE EATOM. 
3()S 
zygii]) 0 |)liyscs wliicli they face. The posterior zygapophyses {'p.z.) are strongly 
])roniinent trihedral ])rocesses, the posterior face of which is nearly vertical, the lower 
l)ears the oval articular surface, while the upper is continuous with the upper surface 
of the arch ; their upper angles are continued as ridges to the base of the neural spine ; 
on the posterior face there is a shallow pit (/'.). The zygantral facets form the 
sides of the deep zygantrum [za.) in the posterior end of the arch ; they are oval in 
outline and inclined to the surfaces of the posterior zygapophyses at a very acute 
angle. The transverse processes {t.p.) are very short and stout ; at their extremities 
they bear the vertically elongated rib-facets, which are convex in all directions above, 
but concave from above downwards below, as in Python ; their lower angles are on 
a level with the ventral border of the centrum. The trefoil-shaped neural canal is 
very small, relatively much smaller than in the recent genus. 
A rib associated with the type vertebra? shows that, while the articular end is just 
as in Python, the shaft is more compressed from before backwards. 
The posterior portion of a left ramus of a mandible (PI. XXVI. fig. 3) of a reptile 
found close to the type vertebra? may belong to this species. The specimen includes 
the angular and articular region, in front of which it is broken away. The articular 
surface {art.) is convex from side to side, and concave from before backwards ; it is 
wider in front than behind, where it terminates in a point ; its anterior border runs 
inwards and forwards, so that the whole surface is somewhat oblique, much as in 
Python. The angle (a??*/.) is thick and not very prominent; it differs from that of 
the mandible of Python in being less sharply marked off from the region in front. 
The inner plate of the jaw, which if complete would run up anteriorly to the coronoid 
lu-ocess, is broken away, but enough remains to show that probably it was separated 
from the outer plate by a deep channel as in Python. The apparent sculpturing of 
the surface of some of the bones (see PI. XXVI. fig. 3 a) appears to be due merely 
to the etching of the surface by drifting sand. If this mandible did actually belong to 
(jigantophis yarstmi, then, judging from its size compared with any vertebra? found, it 
would seem that the head in this animal was relatively much larger than in recent 
snakes ; but more satisfactory material is necessary before any definite conclusion 
can be arrived at. 
C. 10022. As.sociated series of about twenty vertebra? and portions of two ribs. TyP*^ specimen, 
described and figured loc. cit. ; also figured PI. XXVI. fig. 1. The dimensions 
(in centimetres) of one of these vertebra? are : — 
Greatest lieiglit from top of neural spine to end of hypapopliysis. 5 app. 
„ v\ idth (between ends of transverse proci'sses) . . . trl 
'Width between outer angles of posterior /ygaj)op!iyses . . . bm 
„ ,, upper angles of zygosjjliene 2-1 
,, of articular cup of cent rum 
Height of articular cup of centrum I’O 
