occur in greatly preponderating numbers, perhaps a hundred of them to
one smeller.

To return to Bronn's objection. When he says that "for the support of
the Darwinian theory, and in order to explain why many species do not
coalesce by means of intermediate forms, he would gladly discover some
external or internal principle which should compel the variations of
each species to advance in ONE direction, instead of merely permitting
them in all directions," we may, in this as in many other cases, find
such a principle in the fact that actually only a few directions stand
open in which the variations are at the same time improvements, and in
which therefore they can accumulate and become fixed; whilst in all
others, being either indifferent or injurious, they will go as lightly
as they come.

(FIGURE 7. Orchestia Darwinii, n. sp. male.)

The occurrence of two kinds of males in the same species may perhaps not
be a very rare phenomenon in animals in which the males differ widely
from the females in structure. But only in those which can be procured
in sufficient abundance, will it be possible to arrive at a conviction
that we have not before us either two different species, or animals of
different ages. From my own observation, although not very extensive, I
can give a second example. It relates to a shore-hopper (Orchestia). The
animal (Figure 7) lives in marshy places in the vicinity of the sea,
under decaying leaves, in the loose earth which the Marsh Crabs
(Gelasimus, Sesarma, Cyclograpsus, etc.) throw up around the entrance to
their borrows, and even under dry cow-dung and horse-dung. If this
species removes to a greater distance from the shore than the majority
of its congeners (although some of them advance very far into the land