74 Piiget Sound Marine Sta. Pub. Vol. 1, No. 9 



also been found growing on Zostera. Ulva lactuca sometimes grows quite 

 abundantly among Zostera plants. Agardhiella tenera and Polysiphonia 

 species are sometimes found growing on pebbles and shells. This in- 

 cludes all the common plants of this association with the exception of 

 those forms which occasionally drift into the eelgrass. 



Table 6. Composition of the Zostera Association 



DOMINANT SPECIES 



Zostera marina 



PRIMARY SPECIES 



Porphyra naiadum Diatoms 



SECONDARY SPECIES 



Enteromorpha linza Agardhiella tenera 



Polysiphonia sp. Ulva lactuca 



One of the best places to observe the abundance of the algae is 

 on Minnesota Reef, on the eastern extremity of Madrona Peninsula. 

 Here we find represented each of the several associations. The reef is 

 only a few hundred yards long and much less wide, but it presents a 

 variety of conditions and habitats so that many species are found 

 here. The number of species on this reef is so numerous that it has be- 

 come a favorite collecting place for students of algae. On a single day 

 at low tide the writer has observed 48 species of algae growing on 

 and in the immediate vicinity. Plate 14 shows the distribution of algae 

 on Minnesota Reef. 



The following is a list of the algae found on Minnesota Reef and 

 immediate vicinity: 



RHODOPHYCEAE 



l.f Corallina officinalis* 23. Rhodomela larix 



2. Amphiroa tuberculosa 26. Polysiphonia sp.* 



4. Constantinea rosa-marina 27. Polysiphonia sp. 



5. Sarcophyllus californica* 32. Nitophyllura ruprechtianum 



6. Prionitis lyallii* 34. Halosaccion glandiforme* 



7. Grateloupia cutleriae 35. Plocamnion coccineum 

 9. Gloiopeltis furcata* 42. Agardhiella tenera 



10. Microcladia borealis 45. Callophyllis flabellulata 



11. Ceramium codicola* 48. Gigartina radula exasperata 

 16. Ceratothamnion pikeanum 49. Gigartina mamillosa* 



laxum 50. Iridaea laminarioides* 



18. Dasyopsis plumosa 52. Endocladia muricata* 



20. Odonthalia aleutica* 53. Porphyra perforata* 



22. Odonthalia floccosa 55. Porphyra naiadum 



-J-The number preceding each name refers to the number by which it is 

 indicated on the chart. 



♦Those species which are very abundant on this reef. 



