306 WILSON GEE 



tribution ranges from Sitka, Alaska, to as far south as Panama. 

 It commonly occurs in great masses, entirely covering the sides 

 of rocks, and thus affording a great abundance of easily obtain- 

 able material. This species is relatively easily kept in good 

 condition in the laboratory provided the sea water in the dishes 

 is frequently changed and the animals kept in a cool room. 

 The size of the individuals varies considerably, depending 

 largely upon the age of the anemone. Individuals from a few 

 millimetres diameter to several centimetres can be secured, 

 though those about five centimetres in diameter were found 

 most suitable for the greater part of the work presented in 

 this paper. 



At low tide, the thousands of Cribrina exposed on the rocks 

 are in a contracted condition, retaining sufficient water to keep 

 the body tissues in good shape in spite of the desiccation to 

 which they are subjected. When the anemones are strongly 

 stimulated, much of this water is expelled, finding its way out 

 through the mouth opening, the tips of the tentacles, or of 

 the tubercles with which the column and the edge of the disk 

 are covered. Pickering has called attention to this habit in 

 Bunodactis artemisia and Verrill ha's noted the same thing in 

 B. Dowii. Torrey (1906) has observed this reaction in Cribrina 

 xanthogrammica, and considers that "permanent openings prob- 

 ably exist, although difficult to find in sections." This response 

 must occur quite frequently in the life of the animal, since any 

 agency which causes a close contraction of the body must neces- 

 sarily cause the discharge of the surplus water contained in 

 the gastrovascular cavity. The expulsion occurs at the points 

 of least resistance . in the body, and it appears to me that the 

 openings at these points represent temporary ruptures which 

 in the economy of the individual are soon repaired. 



The masses of this species of anemone when exposed on the 

 rocks blend to a quite marked extent with the sand and gravel 

 scattered around them. This is largely due to the habit which 

 Cribrina has of attaching the tips of the tubercles distributed 

 over the column of its body to small gravel, pieces of shell, 

 spines of sea-urchins or any similar material with which they 

 chance to come in contact. The concealing effect is often so 

 great as to cause one to quite overlook large masses of material 

 in the search for anemones. After the specimens have been 



