attended to the recent progress of natural history. For this belief
implies the former existence of links binding closely together all
these forms, now so utterly unlike.
Nevertheless, it is certain that groups of animals have existed, or do
now exist, which serve to connect several of the great vertebrate
classes more or less closely. We have seen that the Ornithorhynchus
graduates towards reptiles; and Prof. Huxley has discovered, and is
confirmed by Mr. Cope and others, that the Dinosaurians are in many
important characters intermediate between certain reptiles and certain
birds the birds referred to being the ostrich-tribe (itself 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 sea-lizards 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.
Lastly, one single member of the immense and diversified class of
fishes, namely, the lancelet or amphioxus, is so different from all
other fishes, that Haeckel maintains that it ought to form a distinct
class in the vertebrate kingdom. This fish is remarkable for its
negative characters; it can hardly be said to possess a brain,
vertebral column, or heart, etc.; so that it was classed by the older
naturalists amongst the worms. Many years ago Prof. Goodsir perceived
that the lancelet presented some affinities with the Ascidians, which
are invertebrate, hermaphrodite, marine creatures permanently attached
to a support. They hardly appear like animals, and consist of a simple,
tough, leathery sack, with two small projecting orifices. They belong
to the Mulluscoida of Huxley a lower division of the great kingdom of
the Mollusca; but they have recently been placed by some naturalists
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