1916 



Muenscher; on Shaw Island Algae 



203 



very abundant in the upper littoral zone; while Codium dimorphtim, Co- 

 dium mucronatiim, Colpomenia sinuosa, Apoglossum decipiens, and Grif- 

 fithsia tasmanica (?) are often found in the extreme lower littoral zone of 

 these shaded rocky shores. 



The algal vegetation on Canoe Island and on the Wasp Islands in 

 general does not differ from that of Shaw Island. Nearly every species 

 was found on each of the different islands {table 1). This probably in- 

 dicates that the currents scatter the spores to all the shores; therefore if 

 a certain alga is not found in a certain place it is probably due to un- 

 favorable environment and not lack of distribution of spores. 



Table 1. Showing the number of species of algae found on Share Island 

 and on the smaller islands around it* 



Total species 



41 I 79 I 40 I 10 



I 14 



103 I 106 



The following localities are of interest because in them are found 

 certain algae, in great abundance, in exceptionally good condition, or 

 species that are otherwise not common or even very rare. These places 

 are indicated on the map by the numbers which precede them (plate 34). 



1. Reid rock is a large submerged mass of rocks near the middle of 

 San Juan Channel. It is marked by a buoy, but can easily be located 

 by the large bed of Nereocystis growing upon it. The Nereocystis plants 

 apparently grow on all of the rock that is less than about 15 meters be- 

 low the surface. Numerous entire Nereocystis plants were removed from 

 their place of attachment, the largest individual observed had a stipe 17 

 meters in length and blades 9 meters in length, making a total length of 

 28 meters. This bed contains the largest and healthiest individuals of 

 Nereocystis that were observed among the San Juan Islands by the writer. 

 The swiftness of the current and the depth of the water seem to be re- 

 sponsible for the excellent condition and immense size of these algae. 

 Many smaller algae, such as Polysiphonia urceolata, Desmarestia aculeata, 



•The 5 Wasp islands refer to Brown, Bird, Knob, Yellow and Cliff islands 

 (plate 33). 



