28 THE DISK. 



itself to a height of three inches, expanding at the 

 extremity as usual : the thickness of the stem is in 

 this case somewhat diminished. 



From the upper part of the cylindrical stem or hody, 

 the disk ahruptly spreads around to the width ahove 

 indicated. In this respect the A. hellis differs so 

 greatly from other littoral species of sea-anemones, 

 that it can never he mistaken hy those who have once 

 seen it. In these the disk is merelv the termination 

 of a short thick column, occasionally a little expanded 

 over the edge ; in hellis, however, the diameter of the 

 disk is generally four times that of the hody, at the 

 point from which it expands. Its form, viewed 

 externally, is that of a shallow cup, hut its surface is 

 in general almost flat, or a very little depressed to 

 the centre. The whole hears a likeness closer than 

 usual to a flower, with a footstalk. The disk is so 

 thin and membranous, that it is continually changing 

 its form ; the margin is frequently bent over out- 

 wardly or inwardly in places ; as it lies on the uneven 

 rock, it accommodates itself to the roughnesses, and 

 is hence often irregularly undulated; it very com- 

 monly bends inward the edge in several places, so as 

 to make puckers or frilled scollopings around the 

 margin. And this surely must be meant by what 

 writers describe and draw as "lobes" to the disk: for 

 of lohes proper it has none ; not the slightest trace ; 

 the outline of the disk is most perfectly and beauti- 

 fully circular ; and I find it often expanded in this 

 state, without any puckering or festooning. (See 

 Plate I, fig. 1.) 



The tentacles are small but numerous : they are 



