204
THE ESSEX NATURALIST.
sharply-pointed teeth, which are sometimes barbed, and would
always be useful for grasping comparatively large fishes for food.
That they actually fed on large prey is shown by the occasional
discovery of whole fishes in the stomach-region of the fossils from
the Lebanon.6 Enchodus itself, which is represented at Grays
by teeth and fragments of jaws, has an especially long and sharp
tooth on the palatine bone. Apateodus has jaws nearly like
those of the existing deep-sea Alepidosaurus7 (fig. 5).
Cimolichthys has some barbed teeth, and Halec has a close series
of sharp conical teeth. The Cretaceous forms themselves are
indeed varied, but fishes of this type have become much more
varied since they retreated to the ocean depths.
Fig. 5. Alepidosaurus ferox, Lowe.
The Enchodonts seem to lead towards the Acanthopterygii
or spine-finned fishes, which include the highest( most specialised)
groups of the Class Pisces. They are represented in the Chalk
only by a few of their most primitive forms which are referable
to the Berycoids and perhaps to ancestors of the Scombroids
(mackerel, etc.). Of the Berycoids the commonest genus in the
Chalk, Hoplopteryx, is especially interesting as still surviving in
the seas off South Australia and New Zealand8 (figs. 6, 7). It
is remarkable that a fish with so complicated an arrangement of
slime-pits on the head should have remained practically un-
changed since the Cretaceous period. As shown by Berycopsis,
also from the English Chalk, the Scombroids were less well
separated from the Berycoids in the Cretaceous period than they
6 J. W. Davis, Trans. Roy. Dublin Society, n.s., vol. iii. (1887), pl. xxxvi., fig. 1.
7 C. Tate Regan, Ann. and Mag. Nat. Hist. [8], vol. vii. (1911), p. 131, fig. 6.
8 C. Tate Regan, Ann. and Mag. Nat. Hist. [8], vol. vii. (1911), p. 5, pl. i.