148 MINNESOTA BOTANICAL STUDIES. 



POOL No. III. 



Location. Mid-tide pool. At a level one half foot below. 

 No. 2. Distance from the ridge twenty feet. 



Exposure to Tide. During high tide filled repeatedly from 

 south and west and subject also to a strong return flow as the 

 waves are thrown back from the edge of the ledge above. 

 Drainage to the south and west. 



Shape and Dimensions. Nearly circular. Greatest diameter 

 three feet. Depth two and one half feet. 



Sides smooth and uniform, almost perpendicular with the 

 edge overhanging at the very top. Bottom covered by stones 

 varying in size from a small marble to rocks two feet in length. 



Flora: Kind and Distribution. 



1. Corallina aculeata. 



Occupies a zone around the rim of pool for three inches. 



2. Amphiroa cretacea. 



Occurs below No. i, creeping down cracks nearly to the bot- 

 tom of the pool. 



3. Amphiroa tuberculosa. 



Associated with No. 2. 



4. Codium mucronatum. 



Occupies a zone around the pool about eight inches from the 

 top. Most abundant on the south side from which the waves 

 enter. 



5 . Codium adhaerens. 



Occurs on south side with No. 4. 



6. Polysiphonia sp. 

 Abundant with No. 4. 



7. Gigartina sp. 



Occurs around the edge of pool in small tufts. 



8. Cladophora. 



A few specimens occur a few inches below the rim of the 

 pool. 



9. Cheilosporum calif ornicum. 

 Occurs on south side below No. i. 



10. Corallina vancouveriensis. 

 Associated with No. i. 



