212 



W. C. ALLEE. 



is deeper and the wave action is less violent. The conditions in 

 the water, so far as investigated, are given in Table III. It will 



Table III. 



Showing Salinity, Temperature, Oxygen Content and pH of Water 

 from Wharf Pilings Association. 1 



be noted that the pH was constant in all locations; that the 

 oxygen content was relatively constant for each location, with 

 the exception of one collection taken at Crane's Wharf just 

 after the passing of a Nantucket steamer which caused a decided 

 increase. There is no evidence of vertical gradients among the 

 factors analyzed to explain the vertical distribution of animals 

 found on the wharf pilings ; nor is there an indication of horizontal 

 gradients along the wharf save in salinity. 



All the animals found in collecting on Crane's Wharf pilings 

 are given in List 2. The figures give an arbitrary means of 

 showing relative abundance and are based on the number of 

 collecting teams reporting each animal in one afternoon's work 

 early in July, 1920. Absence of such figures shows that the 

 animals were not found at that time. 



1 Low tide and bright sunlight throughout. 



