The Devonian period is a range of geological time which falls
in the Paleozoic era, roughly 408 to 360 million years ago. During
this time forests and amphibians made their first appearances.
According to The Columbia Encyclopedia,
The most notable Devonian animals were the jawed and
bony fishes, which appeared in great numbers toward the close
of the period. Conspicuous types were sharks, armored fishes,
lungfishes, and ganoid fishes.
Of these Devonian fishes, H. G. Wells has written in A Short
History of the World
Fishes of a pattern now gone from the earth, and fishes allied
to the sharks and sturgeons of to-day, rushed through the waters,
leapt in the air, browsed among the seaweeds, pursued and preyed
upon one another, and gave a new liveliness to the waters of
the world. None of these were excessively big by our present
standards. Few of them were more than two or three feet long,
but there were exceptional forms which were as long as twenty
In Grendel, the Dragon mentions the Devonian fish as
an example of "nonce-rules" (71); that is, something
new which rises to meet a single occasion. It connotes a fluke
or an accident, randomness which produces more randomness. The
Devonian fish seems to be a good example of this because, as
We know nothing from geology of the ancestors of these fishes.
They do not appear to be related to any of the forms that preceded