se kinds." The saurians have become almost extinct and the
mammal-tribe suddenly shows a most extraordinary variability and power
of development. How is either phenomenon to be explained?

"The disappearance of a group of organisms has been preferably
explained since the time of Darwin, by defeat in the struggle with
superior competitors. If ever an explanation lacked pertinency, it does
so in this case, in which the succumbing group is represented by
gigantic and well preserved animal forms, widely distributed and
accustomed to the most varied methods of nutrition, whereas the
competitor appears in the form of small, harmless marsupials. It would
be equivalent to a struggle between the elephant and the mouse."

We acknowledge with pleasure this clear rejection of Darwinism on the
part of Steinmann.

Steinmann also rejects the natural extinction of those forms, perhaps
from the weakness of old age; whether he is wholly warranted in doing
so, seems somewhat doubtful. He tries to explain the phenomenon on
the basis of the multiple origin of the mammals; and in fact there
is already speculation regarding triple origin, viz: tambreets,
marsupials, and the other mammals. Now if the latter also possessed a
multiple origin, the problem of the extinction of the saurians would,
according to Steinmann solve itself. One would not need to consider the
number of extinct forms as large as is now done. However, he does not
enter upon any closer consideration of this question. But he points
out, for instance, that to-day the shells of mollusks (snails and
conchylia) are regarded as structures that were acquired only in the
course of time for the sake of protection, the disappearance of which,
therefore, implied a disadvantage for the respective organisms. This
transition would be something extraordinary--"but if on the contrary,
one regards the shells as the necessary products of a special kind of
assimilation and of the immoveableness of certain parts of the body,
the gradual disappearance might well be considered a process which may
take place in various animal-groups with a certain regularity in the
course of the phyletic development." The snails devoid of shells, for
instance, may be derived with certainty from those possessed of shells;
this process has very probably also taken place in different genetic
lines.

This view is well worth consideration; it stands in sharp opposition,
in fundamental principles, to the Darwinian ex