rate from behind into the branchial cavity. 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, enla