ADAMSIA. 231 



the others are instantly brought to its aid, and the hermit 

 may soon find that he is more than compensated for the 

 crumbs that fell from his own booty *." Mr. W. Thomp- 

 son states that every shell he saw invested by A. maculata 

 was tenanted by Pagurus Prideauxii. This, Dr. Johnston 

 adds, proves the general union, but that Professor E. Forbes 

 assures him that, on the coast of the Isle of Man, the shells 

 to which the Adamsia attaches itself are seldom inhabited 

 by the hermit-crab. He states also that the Adamsia seems 

 to change its habitation according to its size. 



The first time I observed the Adamsia was in the island 

 of Arran, before I had turned my attention much to zoo- 

 phytes. I was in search of shells, wading in the pretty 

 Highland brook called Glenrosa-burn, where it falls into 

 the sea near Brodick. As the tide was in, the water must 

 have been somewhat brackish. I saw numbers of Trochus 

 magus, and to my great surprise the mollusk, as I thought, 

 had wrapped itself round the outside of the shell. The 

 animal was beautifully spotted, and as I did not then know 

 the appearance of the true inhabitant of Trochus magus, I 



* 'Excursions to Arran, with reference to the Natural History of the 

 Island,' by D. L. Johnstone and Hunter, Paternoster-row, London, and 

 Princes- street, Edinburgh. 



