of the Skull in Peloneustes philarchus. 251 
with them—bore a paroccipital process. In the skull of Plio- 
saurus above mentioned this process is long and has a spatu- 
late expansion at its outer end, which apparently abuts against 
the inner surface of the quadrate at its junction with the 
posterior bar of the pterygoid. 
parvetal a 
Diagrams showing the structure of the skull in Peloneustes. A, from 
above; B, from side.—f., frontal; ju., Jugal; da., lachrymal ; mz., 
maxilla; ma., nasal; orb., orbit; p., parietal; p.f., prefrontal ; 
p.o., postorbital; po, postfrontal; p.ma., premaxilla; sup.orb., 
(?) supraorbital; occ., occipital condyle; g, quadrate; sq., squa- 
mosal. 
The basisphenoid is not sufficiently well preserved for 
description in any of the specimens ; it is entirely covered by 
the pterygoids below. In front of it is seen the bone here 
regarded as a parasphenoid. ‘This is of an elongate lanceolate 
shape and terminates anteriorly in a point. It separates the 
posterior palatine foramina from one another, and anteriorly 
unites with the pterygoids in the manner above described. 
Its upper surface is slightly channelled in the median line for 
about the middle third of its length. In some specimens of 
the skull of Cryptoclidus the posterior part of this bone is 
