206 Sitst Annual Report 
Pelvetia fastigiata (J. Ag.) deToni 
In immense colonies on the rocks of the high tidal zone, forming 
a distinct zone which reaches almost to the upper limits of algal 
growth. 
Cystoseira osmundacea (Mentz.) Ag. 
A frequent component of the beach wrack. Dr. Setchell gives this 
determination with doubt. 
Halidrys dioica Gardner 
Common on the rocks of the lower tidal zone. 
Sargassum agardhianum Farlow 
Common on rocks near low tide mark. 
DICTYOTACEAE 
Zonaria tournefortii 
Dictyopteris zonarioides Farlow 
Dictyota binghamiae J. Ag. 
Dilophus flabellatus Collins 
The above four species are all frequent on rocks of the middle 
tidal zone. 
RHODOPHYCEA 
BANGIACEAE 
Porphyra naiadum C. L. Anderson 
Commonly epiphytic on basal portions of Phyllospadia. 
HELMINTHOCLADIACEAE 
Chantrasia dictyotae Collins 
(Figure 113) 
Abundant as an epiphyte on Dictyota binghamiae. Sporangia .02 
mm. in diameter. 
Nemalion lubricum Duby. 
(Figure 114) 
Common on rocks of the lower tidal zone, especially on the faces 
of rocks exposed to the direct pounding of the heaviest surf. Stem 
commonly 1.4 mm. in diameter. 
Helminthocladia purpurea (Harv.) J. Ag. 
Only seen twice, both times in the lower tidal zone. 
