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Rh and the Sea-Anemone in return acting as a defence and warning-post, and possibly also as a decoy, for the benefit of the Crab. But, though the mutual advantage of the association is plain enough, the absolute and essential necessity of it is not so plainly seen, and it is reasonable to imagine that when in the course of growth the Hermit-Crab has to seek a new and larger shell, the partnership with the Sea-Anemone can be dissolved by simple withdrawal, without dangerously affecting the life of either individual—at any rate until such time as each can find a new partner of suitable size. In other words, there is no adaptation of either animal to the other, and each seems capable of existing apart from the other. In the present case there is no shell to act as introduction to and bond between the two animals; and the Sea-Anemone, which is a colonial form with a spreading cœnosarc, merely forms a sheet, which the Crab simply tucks under its telson by one end and pulls over its back by the other end—the polyps seeming to have no power of adhesion, and to depend on the Crab for a fast hold.

"The nearest approach to this state of affairs is found in Parapagurus pilosimanus, which, when full-grown, lives in a cavity hollowed out of the coenosarc of a colony of a large species of Epizoanthus. But in this case the individual Hermit-Crab and Sea-Anemone start their partnership with an empty mollusc-shell, which in course of time, as the occupants increase in size, becomes absorbed, so that at last the Crab is entirely dependent on the polyp-colony for the protection of its soft abdomen. But even here, though the association seems to have become much more intimate and permanent, there seems to be no essential adaptation of either animal to the other, nor does it appear to be beyond the bounds of possibility that each might exist—though its existence might not be so complete and secure—apart from the other.

"In the case of the new form of Hermit-Crab, now described, there is no evidence of the intervention of a shell, or other adventitious support, at any stage. Captain Anderson dredged 205 specimens, of both sexes and all ages, and in every observable instance the parent polyp of the protective colony appears to have settled on the hinder end of the abdomen of the Crab, and to have gradually spread by budding as the latter increased in size; so that the intimate and immediate connection between the two animals appears to be, from the first, a necessary one. In other words, the peculiar interest of the case is that the two animals seem to have become directly adapted to one another, and to be incapable of a separate and independent existence."

August last there was published at St. Petersburg the first number of the 'International Review of Fisheries and Fishculture,' of which the