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(without typos) from the publisher. Not indexed. Not illustrated.
1890 Excerpt: ... next branch, in which the highly aberrant
compressed Ast. Callenoti appeared. This aberrant tendency was
still more decidedly brought out in the more rapid production of
similar, but more compressed and involute, forms in Oxynoticeras.
In this, also, the highest specialization was reached by the
introduction of a new structure, the hollow keel, as a nealogic and
ephebolic characteristic. The smooth variety of Psil. planorbe, and
its immediate congener, Psil. caliphylr htm, were of course the
most primitive forms which occurred in the Lias, and we can treat
the whole of the two stocks as a connected group arising in Central
Europe from the smooth variety of planorbe, though, as a matter of
fact, this is probably artificial. The actual process of the
evolution of the second branch, and probably of Caloceras, as will
be explained in Chapter III., took place in the basin of the
Northeastern Alps, and the forms found in Central Europe were
migrants. When arranged naturally the genera appear as in the
Summary Plates, as an assemblage of distinct and more or less
divergent series. We have considered each separate genetic series
as a genus, because it was necessary to do this, or else use a
cumbersome trinomial or quadrinomial descriptive nomenclature. Even
with the aid of binomials, we have not been able to speak of any
series under one name as a single species. Had this rule been
adopted, i. e. to treat each series as a single species, the
opinions of paleontologists are not now in its favor, and probably
no one would have followed us in practice, however much disposed
theoretically to praise our conservatism. Even Quenstedt in his
most recent work has proposed names for the different groups of
Arietidae all ending in "ceras." They are highly appropria...
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