240 SEPTEMBER. 



If the Crab shifts his quarters and leaves the Adamsia 

 behind, the association is broken, and we should con- 

 stantly find Paguri without Adamsice, and Adamsice 

 without Paguri. But we find neither the one nor 

 the other. 



On the other hand, if Adamsia is able to shift its 

 quarters also, how does it proceed in its search for a 

 new shell ? If it forsakes the old tenement at the 

 same time as the Crab, and together with it takes 

 possession of the new one, by what means is unity of 

 will and action secured? What communication of 

 thought takes place from the one to the other ? As the 

 Adamsia does not adhere to the Crab, but to the shell, 

 that is, as they are independent of each other's move- 

 ments, who takes the initiative? Who goes to seek 

 the lodging? And at what point of the transaction 

 does the other come in? All these questions I had 

 mused upon with interest ; and at length received some 

 light towards their solution. 



On the 10th of January, 1859, 1 obtained, by dredging, 

 in Torbay, a specimen of Adamsia palliata, about half- 

 grown, on a rather small shell of Natica monilifera, 

 tenanted by a Pagurus Prideauxii, . which seemed 

 already too big for his habitation. Having put them 

 into a well-established tank of large dimensions, the 

 contents of which were in excellent condition, I sue- 



