6582 Radiata. 



would have done, at once shift into the new house. Having turned it 

 mouth upward, he took hold of the outer and inner lip each with a claw, 

 and began to drag it about the tank. Occasionally he relinquished 

 the hold of one claw, and probed the interior in the usual manner, and 

 then resumed his march. I watched the proceeding for an hour or 

 more, when, having other work to do, I left him alone. 



The thought did occur to me, — Can this delay be intended to make 

 the Adamsia cognizant of what is in contemplation, and to prepare it 

 for the change ? But 1 dismissed it as unlikely. 



After about an hour's absence I returned to the examination. The 

 Pagurus was comfortably lodged in his new abode, and the old one, 

 which now looked small indeed, lay deserted at some little distance. 

 I eagerly turned the latter over, to see what was the condition of 

 Adamsia. Lo ! no Adamsia was there ; and the Pagurus, presently 

 approaching the front of the tank, I saw, to my great gratification, that 

 the old association was unbroken. There was the Adamsia, with one 

 wing adhering to the lip of the new shell, and apparently the opposite 

 wing also ; but from the position of the group, this I could not be quite 

 certain of. The situation of the zoophyte was quite normal, — the 

 centre immediately below the breast of the crab, and in contact with 

 the inner lip of the shell, while that wing which I could clearly see 

 was creeping round upon the outer lip. 



Examining now more closely the condition of things, with a lens, I 

 saw that the central part of the Adamsia\s base was adherent by a small 

 point of its surface to the under thorax of the crab, between the bases 

 of the legs. 



Now this adhesion to the crab is a circumstance which, so far 

 as I know, never takes place in the ordinary relations of the ani- 

 mals ; and therefore I cannot but think it an extraordinary and 

 temporary provision for the removal of the Adamsia from the old 

 to the new shell, and for the correct adjustment of its position on the 

 latter. 



How then can we avoid the conclusion, that as soon as the crab had 

 found the new shell to be suitable for exchange, the Adamsia also was 

 made cognizant of the same fact ; and that during the two hours which 

 followed, the latter loosened its adhesion to the old shell, and, laying 

 hold of the bosom of its protector, was by him carried to the new house, 

 where immediately it began to secure the like hold to that which it had 

 just relinquished ? 



But what a series of instincts does this series of facts open to us ! 

 The knowledge by the crab of the qualities of the new shell ; the 



