210 Puget Sound Marine Sta. Pub. Vol, 1, No. 18 



92. Chaetomorpha sp. — uli, r. 



93. Hormiscia tetraciliata Frye and Zeller — lli, c. 



94. Ecbellocystis sp. — uli, c. 



95. Ulva lactuca L. — lli, va. 



96. Enteromorplia linza (L.) J. Agardh — lli, va. 



97. Enteromorpha intestinalis (L.) Link — li, c. 



98. Enteromorpha clathrata (Roth) Greville — Lj, r. 



99. Enteromorpha prolifera (Fl. Dan.) J. G. Agardh — li, c. 



100. Chlorochytrium inclusum Kjellman — sli, c. 



MYXOPHYCEAE 



101. Dermocarpa fucicola Saunders — li, c. 



102. Calothrix Crustacea Thur. — uli, r. 



103. Arwhaena variabilis Kiitzing — uli, r. 



SUMMARY 



1. In general the shore algae of Shaw Island are not very different 

 from those of San Juan Island in distribution nor in the number of species 

 represented. Of the 12 species that were not found on both islands 2 

 were found only on Shaw Island, and 10 were found only on San Juan 

 Island. Of the latter, the 2 most important species are Egregia tnenziesii 

 and Hedopyllum sessile, which grow only on the rougher shores. 



2. The algae of Shaw Island are also well distributed on the shores 

 of the smaller islands around it (table 1). This seems to indicate for 

 most of the species, many spores efficiently scattered by waves and currents. 



3. The structure of algal vegetation occupying relative positions 

 ajbove or below the low-tide line is greatly modified by the character of ->. 



-flaost—o£_the species, many spores efficiently •^oaH^t^vt^fi i*j - Hif^ -iTmyAr; ^(ry\ ^ 



currents. 



4. The absence of certain species of algae from certain shores on 

 Shaw Island and San Juan Island is usually due not to lack of distribu- 

 tion but to unfavorable environment. 



The writer is indebted to various members of the Algology class of 

 the Puget Sound Marine Station for assistance in making simultaneous 

 observations on different shores during favorable tides. 



