of the Skull in Peloneustes philarchus. 247 
gone; it can, however, be seen that the bone gradually 
narrows to a thin backward prolongation which extends 
about 4°5 centim. behind the last tooth. The upper edge of 
the hindermost portion upites with an element which appears 
to be a jugal, the relations of which will be described below ; 
the lower edge forms the junction with the transpalatine 
above mentioned. 
The vomers are extremely large; in specimen 4, from 
which the following description of the palate is mainly taken, 
they measure 29 centim. in length, or nearly half the total 
length of the skull (61 centim.).Anteriorly they run 
between the premaxille, terminating in front in a point. 
From the premaxille to the anterior angle of the internal 
narial aperture.they unite externally with the maxille, in- 
creasing gradually in width. At the nares, of which they 
form the inner border, they are contracted, measuring 
together about 3 centim. across at the narrowest part. Their 
widest point is immediately behind the nares, from which 
openings their border runs inwards and backwards in a curve, 
convex posteriorly, in the anterior half of which they form a 
squamous union with the palatines, and in the posterior half 
with the pterygoids, which thus completely shut out the 
palatines from the middle line. 
The palatines are bounded externally by the maxille, 
internally by the internal nares, of which they form the 
postero-external margin, by the vomers, and, to the greatest 
extent, by the pterygoids. In no specimen is the whole of 
the posterior border of the palatines preserved, but its inner 
portion united with the anterior edge of the lateral wing of 
the pterygoid in a straight suture running nearly at right 
angles to the long axis of the skull, while the outer portion 
seems to have joined the transpalatine, there having been no 
vacuity in front of this bone, or, at any rate, only a small 
one. 
The tnternal nares, the borders of which, as has already 
been mentioned, are formed by the vomers internally and the 
maxille and palatines externally, are slits measuring approxi- 
mately 3 or 4centim. long by 1 centim. wide. Their anterior 
angle lies about 28 centim. from the anterior extremity of the 
skull. 
In specimen 1 the internal nares open considerably in front 
of the external; this anomalous condition may be partly 
accounted for by the crushing which the skull has undergone, 
but, even allowing for this, the arrangement would be essen- 
tially the same. ‘his relative position of the external and 
internal narial openings is well shown in askull of Pliosaurus 
