102 
ACTIXOPTERYGII. 
P. 8633. The type specimen, being the head and part of the abdo¬ 
minal region exposed from the right side, shown of the 
natural size in PL VIII. Gault, Polkestone. The 
anterior ethmoidal end of the cranium is slender and 
pointed, while the supraoccipital (s.ocr.) rises as usual 
into a rounded median crest. The ectethmoid or pre¬ 
frontal (pr./.) is relatively large and stout, with the 
usual flattened facette for the articulation of the anterior 
thickened end of the palatine The premaxillae 
(pmi\) are deeper than long, and meet in the middle line 
in front of the ethmoid. Their teeth are very small, but 
must have been slightly larger than those of the maxilla, 
which are quite minute. The maxilla (nix.) displays its 
articulation with the palatine in front, and is overlapped 
behind by the cheek-plates : its oral margin is excavated 
just behind its anterior end, hut is strongly convex 
further back. Its minute teeth are fi.xed just within the 
rugose border. The mandible is remarkably deep, and 
the symphysial end of the dentary (cl.) slopes slightly 
backwards and downwards. Its oral margin is only 
exposed in front, where the slender, styliform teeth are 
considerably larger than any shown in the upper jaw. 
There are remains of large, smooth, suborbital cheek- 
plates (s.o.); and the sclerotic of the eye {scl.) is well 
ossified. The preoperculum (p.op.) forms a great tri¬ 
angular expansion, rather thin and nearly smooth, with 
a slightly thickened anterior border. The operculum (opl) 
and other plates are fragmentary. Some of the anterior 
vertebral centra are slightly longer than deep, and display 
the characteristic pittings. The bases of some of the 
pectoral fin-rays {i:>ct.) are very large and broad. There 
are also obscure remains of large, thin scales. 
Fiir chased., 1897. 
Ichthyodectes minor (Egerton). 
1850. Hypsodon minor, Sir P. Egerton, in E. Dixon, Geol. Sussex, 
p. xiv, pi. xxxii.* fig. 9. 
1877. Ichthyodectes minor, E. T. Newton, Quart. Journ. Geol. Soc. 
vol. xxxiii. p. 520, pi. xxii. fig. 14. 
Type. Imperfect mandible; Eritish Museum. 
A species known only by remains of the mandible, of moderate 
size. Oral border of dentarv nearly straight, with a slight con¬ 
vexity towards its anterior end; its outer face not sharply bulging 
