82 



Actinia mesembry&nihemum. 



Actinia mesembryanthemum. 



when they lie relaxed and in a state of partial expansion, very 

 indicative of apathy and lazy repose: others, having chosen a 

 little rocky basin, filled with the purest water, for their resi- 

 dence, are generally seen expanded ; the tentacula all dis- 

 played, and held so still, that no ripple or current alarms the 

 unsuspicious crab or snail as it creeps within the circle of 

 these tubulous suckers, from whose embrace it will certainly 

 not escape. Actinia mesembryanthemum never, so far as I 

 have observed, emits from the mouth, like some other species, 

 any thread-like tangled filaments ; nor does it seem to have 

 the power of protruding the membrane of the stomach in the 

 form of vesicular lobes. Gaertner says that " the colour of 

 its body is always red in the summer, but changes into a 

 dusky green, or brown, towards the latter end of autumn," a 

 remark which certainly does not hold good on the northern 

 shores of England, where the red and dusky green varieties 

 may be found at all seasons. 



The body is an inch, or an inch and a half, in diameter, hemi- 

 spherical when contracted, very smooth, and of a liver brown 

 or olivaceous colour ; the base is generally of a uniform green- 

 ish colour encircled with an azure blue line, but frequently it 

 is streaked with red, and the blue marginal line is wanting ; 

 tentacula numerous, multiserial, of the colour of the body, 

 entirely retractile ; margin of the oral disk ornamented with 

 a circle of azure blue tubercles, which are formed by papillary 

 projections of the proper substance of the body, covered over 

 on the top with a thick layer of dense blue matter ; in which, 

 as well as in the skin generally, minute fusiform calcareous 



