64 Puget Sound Marine Sta. Pub. Vol. 1, No. 9 



The associations are named after one of the most dominant species 

 included within them. Under each association are listed: (a) The 

 dominant species, or those which are the most common throughout the 

 association; (b) the primary species, or those which often form prom- 

 inent societies; (c) the secondary species, or those which are found only 

 occasionally and almost never occur in great abundance in any one place. 



Between the high tide line and the low tide line, and thus in the 

 littoral zone, we find three distinct associations extending more or less 

 parallel with the water line, as follows : 



1. The Endocladia Association 



This association occupies the upper part of the littoral zone, form- 

 ing a belt of varying width, but averaging about one meter. Where 

 the waves dash against the rocky shore and form a spray, this asso- 

 ciation often reaches above the high tide line. In such places Porphyra 

 perforata is often found. Examples of this are seen on Minnesota Reef, 

 Cattle Point, Kanaka Bay, and along the west coast. Endocladia muricata 

 is the most abundant species of this association. The plants are very 

 small, erect and branched, and seem to be well adapted to resist the 

 beating of the waves at high tide and the desiccating power of the 

 sun when the tide is low. 



Where fresh-water springs enter the salt water, we find Entero- 

 morpha linza in great abundance. The plants are often somewhat de- 

 formed, specially those growing highest up the shore. These have been 

 observed to grow one meter above the high water line, and there are often 

 very pale or almost white. Within these groups of Enteromorpha linza 

 one often finds Calothrix Crustacea, Anabaena variabilis and Cylindro- 

 spermum stagnale growing in great abundance. The best places for col- 

 lecting the above algae are near the lime kiln on the west coast of the 

 Island and at "Nebraska Springs" {Plate 10). 



In very rough places where tide pools are left in the pockets of 

 the rocks, it is not uncommon to find small, much branched, yellow, al- 

 most unrecognizable specimens of Prionitis lyallii growing in the warm 

 water. In the same pools one may also find small scraggly specimens 

 of Rhodomela larix, specially where there is a little sand on the bottom 

 of the pool. Gigartina mamillosa is also found in this association, al- 

 though the individuals are much smaller and more branched than those 

 which grow in the lower associations. Near the lower boundary are found 

 individuals of Gloiopeltis furcata and Fucus evanescens, which really 

 belong in the Fucus Association below. 



