STUDIES IN MARINE ECOLOGY. 



239 



of variation of extremes one substitutes the more complex index 

 shown in Table XV., which combines the amount of variation 

 with the location of extremes, the series is arranged by the data 

 given here exactly in order of ecological age. 



Table XV. 



Eroding Shore Series. 



Showing range of variations of temperature, oxygen content, salinity, and pH 

 at the stratum most studied in each animal association; all tide stages considered. 

 The last two associations are added for comparative purposes. 



Ordinal ranking is based on amount of variation and relative location of extremes. 



Association. 



Salinity 



in 



Per Cent. 



Oxygen 

 in c.c. 

 Liter. 



Temperature 



in Degrees 



C 



04 





pH. 



■B C 



Ranking. 



£ 5 



73 .S 



CM 



Eg 



Pi 



Open 



Wharf 

 pilings. . . . 



Exposed 

 rocks 



Rockweed 



My a 



Melampus 



3.02 

 3.14 0.12 



2.97 

 3-13 0.16 



2.94 

 3.04 0.10 ,; 

 2.97J 

 3.02 0.5 



3-93 

 5-43 



1.50 



4.06 

 6.00; 1.94 



3-62 

 8.56 

 4-75 

 8.56 



4-94 

 3.81 



19 



2.0 1.5 



2.0 1. s 



3-0 3 



I 



4-0,4 



.0 — 



.0+ o, 



8.0 

 8.0 



8.0 



8-3 

 8.0 

 8.3 



0.0 



0.3 

 0.3 



5-5 

 6.5 



13-5 



14-5 



13 



26.5 

 29-5 



b. The Depositing Shore Series. — The flats series intergrades 

 more closely than the different associations of the rocks. The 

 conditions characteristic of each association are most marked at 

 low tide and these are summarized as averaged data in Table 

 XVI. As might be expected the average salinity at low tide 

 decreases regularly as one goes back on the flats. But this is 

 the only factor considered that shows such a regular relationship. 

 With the others the conditions over the sand bar approach those 



1 Estimated between tides. 



2 Estimated for purposes of comparison. 



"Combined ranking" refers to the rankings given in Tables XIV. and XV, 

 The final ranking is based on the preceding column. 



