The Descent of Man

evidently a widely-diffused remnant of a larger
group) and the Archeopteryx, that strange Secondary
bird, with a long lizard-like tail. Again,
according to Prof. Owen (22. 'Palaeontology'
1860, p. 199.), the Ichthyosaurians—great sealizards
furnished with paddles—present many
affinities with fishes, or rather, according to
Huxley, with amphibians; a class which, including
in its highest division frogs and toads, is
plainly allied to the Ganoid fishes. These latter
fishes swarmed during the earlier geological
periods, and were constructed on what is called
a generalised type, that is, they presented diversified
affinities with other groups of organisms.
The Lepidosiren is also so closely allied
to amphibians and fishes, that naturalists long
disputed in which of these two classes to rank
it; it, and also some few Ganoid fishes, have
been preserved from utter extinction by inhabiting
rivers, which are harbours of refuge, and
are related to the great waters of the ocean in
the same way that islands are to continents.