that 'Avicula', 'Mytails', 'Chiton', 'Natica', 'Patella', 'Trochus',
'Discina', 'Orbicula', 'Lingula', 'Rhynchonella', and 'Nautilus', all
of which are existing 'genera', are given without a doubt as Silurian in
the last edition of 'Siluria'; while the highest forms of the highest
Cephalopods are represented in the Lias by a genus, 'Belemnoteuthis',
which presents the closest relation to the existing 'Loligo'.

The two highest groups of the Annulosa, the Insecta and the Arachnida,
are represented in the Coal, either by existing genera, or by forms
differing from existing genera in quite minor peculiarities.

Turning to the Vertebrata, the only Paleozoic Elasmobranch Fish of which
we have any complete knowledge is the Devonian and Carboniferous
'Pleuracanthus', which differs no more from existing Sharks than these
do from one another.

Again, vast as is the number of undoubtedly Ganoid fossil Fishes, and
great as is their range in time, a large mass of evidence has recently
been adduced to show that almost all those respecting which we possess
sufficient information, are referable to the same sub-ordinal groups as
the existing 'Lepidosteus', 'Polypterus', and Sturgeon; and that a
singular relation obtains between the older and the younger Fishes; the
former, the Devonian Ganoids, being almost all members of the same
sub-order as 'Polypterus', while the Mesozoic Ganoids are almost all
similarly allied to 'Lepidosteus'.*

[footnote] *"Memoirs of the Geological Survey of the United
Kingdom.--Decade x. Preliminary Essay upon the Systematic
Arrangement of the Fishes of the Devonian Epoch."