A MUTUAL BENEFIT SOCIETY 167 
at the bases, the chelipeds very unequal, and the eleven 
pairs of branchize distributed in couples to the third max- 
illipeds and three following appendages, while the fourth 
pair of legs have the three remaining pairs of branchie. 
But it differs from Hupagurus as well in the structure or 
the branchiz as in having well-developed pairs of male 
appendages on the first and second segments of the pleon. 
The type species, Parapagurus pilosimdnus, Smith, has a 
great range in depth, since American dredging expeditions 
have taken it at thirty or forty stations in the Atlantic 
between deeps of 250 to 2,221 fathoms. Low down in the 
ocean a species may be prolific, for at 319 fathoms nearly 
four hundred specimens were taken at once. 
Notice has often been taken of the curious habit which 
Hupagurus Prideaux has of associating itself with the sea- 
anemone, Adamsia palliata. Surmises are sometimes made 
as to the advantages which the companions may hope to 
obtain from the alliance. Theanemone may obviously obtain 
a greatly increased range for supplies of food, by the 
superior locomotive powers of the hermit, and though the 
weight of both anemone and shell may seem an unneces- 
sary encumbrance to the crustacean, that objection is 
gradually diminished by the circumstance that the anemone 
in course of time almost entirely absorbs the shell.. On 
the other hand the presence of the anemone may be a very 
valuable protection to the hermit, since numerous fishes 
are in the habit of swallowing these recluses, shell and all, 
merely spitting out the shell after they have digested its 
inmate. But it is most probable that to many fishes an 
Adamsia palliata would be by no means an agreeable 
morsel, even when flavoured with crab-sauce. It is also 
not unlikely that the anemone may contribute to the com- 
missariat by throwing out its darts as some swift gliding 
shrimp passes by, and thus reducing it to a condition in 
which it can be captured by the pagurid. This alliance, 
however, which is so familiar, is very far from being the 
only one in this legion of the Crustacea. Rather it may be 
regarded as a well-known example of a very prevalent 
habit. Thus upon shells containing Hupagurus pubescens 
