A MUTUAL BENEFIT SOCIETY 167 



at the bases, the chelipeds very unequal, and the eleven 

 pairs of branchiae distributed in couples to the third max- 

 illipeds and three following appendages, while the fourth 

 pair of legs have the three remaining pairs of branchiae. 

 But it differs from Eupagurus as well in the structure oi 

 the branchiae as in having well-developed pairs of male 

 appendages on the first and second segments of the pleon. 

 The type species, Parcvpagurvs pilosimcmus, 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 

 TSupagurus Prideavx 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. The anemone 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 

 Admnsia 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 JEwpagurus puhescens 



