ITS LOCOMOTIVE POWEES. 185 



space, must include a good many small ones ; gene- 

 rally they are of all sizes, from the gigantic forefather 

 of the family to the tiny great-grandchildren that are 

 scattered romid his base, no larger than peas. In 

 general all the members of each group are of the 

 same hue ; as they are, I presume, strictly one family. 

 Yet one now and then sees an individual of quite 

 another colour in the gi'oup ; a circumstance to be 

 accounted for on the supposition of an accidental in- 

 trusion on a ground already occupied. Flat stones, 

 but more commonly large bivalve shells — such as 

 oysters, pectens, and pinn» — are the sites selected for 

 the colonies of this Actinia. 



Dr. Johnston's statement, that *' A. diantlius is a 

 permanently attached species, and cannot be removed 

 from its site without organic injury to the base," is 

 not confirmed by my experience. I find that it can 

 be removed by the fingers without any difficulty, and 

 that it adheres again to a fresh place with the same 

 readiness as other Actinice. I have now in my Aqua- 

 rium several specimens of large size, which I dis- 

 placed in the usual manner, from their oyster-shells, 

 by shoving them oft" carefully with the back of my 

 finger-nails, and which I merely set down on the 

 pieces of rock-work. I found them firmly fixed in the 

 course of an hour or two, and tliey have manifested 

 no disposition to unsettle themselves since, though 

 they have been there for several weeks. On the other 

 hand, one which I had put in with the shell to which 

 it was affixed, presently crawled spontaneously from 

 his original site, and took up a new abode on the rock- 

 work. The change was eff'ected by the ordinary 



