Il8 W. J. CROZIER. 



The correlation, therefore, between a normal intertidal habitat 

 and the practice of so contracting the body as to conceal the 

 tentacles, decrease the surface for evaporation, and present a 

 smoothly rounded exterior surface, is decidedly worthy of study. 

 A variety (prunicolor Verr.) of A. bermudensis was found 

 in bays on the south shore of Bermuda not under stones, but in 

 small tide pools open to the sun, and also within the tidal zone. 

 This variety is of a brownish hue, whereas the ordinary A. 

 bermudensis is deep red. The color difference, apparently the 

 only feature separating the two forms, was constant, and was 

 even seen in young taken from the gastrovascular cavities of 

 adults; the young of the red forms were always pink or scarlet, 

 those of the brownish forms a light prune-color. The occurrence 

 of such color differences has also been noted in related forms. 

 Elmhirst and Sharpe ('20) state that the deep red A ctiniaequina 

 becomes brown in the laboratory, and that the change "breeds 

 true" a remarkable observation, if correct, and one which 

 should be followed up; it corresponds well with the conditions 

 known in A. bermudensis. The red pigment of the latter species, 

 readily extracted by acetone, is changed to a brownish hue by 

 sunlight. The brownish anemones close up in the usual manner 

 when the tide falls. 



A . bermudensis reproduces " viviparously " throughout the year. 

 Experiments could therefore be made with young actinians 

 "born" in the laboratory or taken from the coelenteron of adults 

 which had never themselves been directly exposed as free 

 individuals to the action of the tidal rhythm. 



When the adults were removed from the natural location at 

 low water and placed in an aquarium, they immediately relaxed 

 and the tentacles were extended. After variable periods, of 

 several hours, in non-circulating water, they closed again, al- 

 though still completely covered by water. In a group of twenty 

 individuals which were on one occasion (in January, 1917) placed 

 in an aquarium, the period elapsing before closure was about 

 three hours. These particular actinians all came from very 

 nearly the same level above low water, and since most of them 

 after a time opened again, I was led to look for a tidal rhythm. 

 In point of fact, however, it is more than doubtful that any 



