262 
ACTINOPTERYGII. 
exhibits a characteristic gentle curvature, with the con¬ 
cavity upwards ; and its outer face is remarkably convex 
and smooth, with an incurved lower border. Of the two 
enlarged mandibular teeth, one occurs on the right, but 
both are preserved on the left; they are slightly recurved, 
apparently compressed to a sharper edge in front than 
behind, and the basal part of the outer face is marked by 
very delicate vertical striations. Six similar, but relatively 
small and short teeth, are preserved posteriorly on the 
right, while four remain on the left; of those on the 
right, the hindermost is the largest. Another similar 
though small tooth is seen just in front of the enlarged 
teeth on the left, and between this and the anterior end 
of the jaw there is a diminishing series of recurved 
denticles. At the hinder end of the right cheek part 
of the quadrate bone {qu.) is exposed ; and immediately 
behind this there is the much-thickened anterior border 
of the preoperculum Q:>.op.). Caqqron Coll, 
P. 4512. A still smaller skull broken across the middle and in some 
respects more imperfect than the type specimen, shown of 
the natural size from both sides and above in PI. XIY. 
figs, 2, 2a, 2 6; English Chalk. The very narrow 
cranium, sharply compressed above the otic region, is 
indicated as before; and the remarkably acute snout is 
especially well shown. On both sides there are remains 
of extensive though delicate postorbital cheek-plates ( 5 . 0 .); 
and the anterior attenuated ends of the characteristic 
premaxillae {pinx.) are displayed apposed to the slender 
ethmoidal region and apparently just meeting in front. 
The two enlarged premaxillary teeth are partly shown on 
both sides (i, ii), but the second on the left seems to be 
a little displaced through fracture. The smooth, delicate 
mandible is much broken ; but the extent of the small 
articulo-angular element {ag.') is seen especially on the 
right, and there are remains of the characteristic small 
teeth on both sides. Enniskillen Coll, 
49067. Group of remains of a small fish, comprising the anterior 
end of the right premaxilla, a quadrate, two vertebral 
centra, and other bones; Chalk, Kent. The anterior 
portion of the premaxilla is shown from the outer aspect 
(PI. XIII. fig. 6) and bears the two enlarged teeth, which 
seem to display their normal proportions and mode of 
