ur times the bulk and size of
the teeth of the hugest reptile of this species that now lives. The
dorsal spine of its contemporary, the Gyracanthus, a great placoid, much
exceeded in size that of any existing fish: it was a mighty spear head,
ornately carved like that of a New Zealand chief, but in a style that,
when he first saw a specimen in my collection, greatly excited the
admiration of Mr. Ruskin. But one of the most remarkable weapons of the
period was the sting of the Pleuracanthus, another great placoid of the
age of gigantic fishes. It was sharp and polished as a stiletto, but,
from its rounded form and dense structure, of great strength; and along
two of its sides, from the taper point to within a few inches of the
base, there ran a thickly-set row of barbs, hooked downwards, like the
thorns that bristle on the young shoots of the wild rose, and which must
have rendered it a weapon not merely of destruction, but also of
torture. The defensive armor of the period, especially that of its
ganoids, seems to have been us remarkable for its powers of resistance
as the offensive must have been for their potency in the assault; and
it seems probable that in the great strength of the bony and enamelled
armature of this order of fishes we have the secret of the extremely
formidable character of the teeth, spines, and stings that coexisted
along with it.

[Illustration: Fig. 59.

CARCHARIAS PRODUCTUS.

Cutting Tooth. (_Miocene._)]

[Illustration: Fig. 60.

PLACODUS GIGAS.

Crushing Teeth. (_Trias._)]

Such of the fishes of the present time as live on crustacea and the
shelled molluscs,--such as the Wrasse or rock-fish family, and at least
one of the Goby family, the sea-wolf,--have an apparatus of crushing
teeth greatly more solid and strong than the teeth of such of their
contemporaries as are either herbivorous or feed on the weaker families
of their own class. A similar remark applies to the ancient sharks, as
contrasted with those of later times. So long as the strongly-armed
ganoidal order prevailed in nature, the sharks were furnished with
massive crushing teeth; but when the ganoids waned in creation, and the
soft-scaled cycloid and ctenoid orders took and amply filled the place
which they had left vacant, the well known modern form of sharks' teeth
was introduced,--a form much rather suited for cutting soft bodies than
for crushing hard ones. In fine, the offensive weapons of the times of
the Coal Meas