(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
and even upon mountains of a thousand feet in height, such as O.
tahitensis, telluris, and sylvicola), its male differs still more from
all known species by the powerful chelae of the second pair of feet.
Orchestia gryphus, from the sandy coast of Monchgut, alone presents a
somewhat similar structure, but in a far less degree; elsewhere the form
of the hand usual in the Amphipoda occurs.
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