Now these crabs,
which have become more or less estranged from the water, belong to the
most different families--the Raninidae (Ranina), Eriphinae (Eriphia
gonagra), Grapsoidae (Aratus, Sesarma, etc.), Ocypodidae (Gelasimus,
Ocypoda), etc., and the separation of these families must doubtless be
referred to a much earlier period than the habit of leaving the water
displayed by some of their members. The arrangements connected with
aerial respiration, therefore, could not be inherited from a common
ancestor, and could scarcely be accordant in their construction. If
there were any such accordance not referable to accidental resemblance
among them, it would have to be laid in the scale as evidence against
the correctness of Darwin's views. I shall show hereafter how in this
case the result, far from presenting such contradictions, was rather in
the most complete harmony with what might be predicted from Darwin's
theory.
(FIGURE 1. Melita exilii n. sp., male, enlarged five times. The large
branchial lamellae are seen projecting between the legs.)
A second example.--We are already acquainted with four species of Melita
(M. valida, setipes, anisochir, and Fresnelii), and I can add a fifth
(Figure 1), in which the second pair of feet bears upon one side a small
hand of the usual structure, and on the other an enormous clasp-forceps.
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