220 G. H. PARKER 



Unable to escape, it was now gradually swallowed by the sea- 

 anemone. Thus the suction exerted by the tentacles is an effec- 

 tive element in enabling the Cribrina to catch and hold its prey. 

 But the tentacles are not the only organs of suction possessed 

 by Cribrina. Below the row of whitish acrorhagi that border 

 the oral margin of the column of this sea-anemone run vertical 

 rows of tubercles. Each row extends more or less regularly 

 from the oral to the pedal disc and may contain as many as fifty 

 members. The tubercles are low and terminate externally in 

 a disc-shaped face in the center of which there is a depressed 

 slit or irregular opening. Each tubercle resembles more or less 

 closely the contracted ambulacral foot of a starfish. Most of 



Fig. 1 Oral view of a preserved Cribrina showing fragments of shell and 

 pebbles attached to the column; three-fourths natural size. Photograph by Dr. 

 S. Hecht, 



the tubercles are well drawn back into the flesh of the sea- 

 anemone but not a few are somewhat extended and have at- 

 tached to their outer ends fragments of shell or stone (fig. 1). 

 In some instances several tubercles are attached to the same 

 piece of shell, but in many cases each fragment is held by a 

 single tubercle. These bits of shell and stone are so abundant on 

 the column of Cribrina that when it contracts they form a com- 

 plete covering for it and render it almost indistinguishable from 

 the surrounding beach material. This shelly covering probably 

 shields the animal from the force of the waves and from desicca- 

 tion. It does not seem to be in the nature of a protective re- 

 semblance, for apparently these sea-anemones are not eaten by 

 other animals. 



When an attempt is made to pull off the fragments of shell 



