14 Bulletin Wisconsin Natural History Society [Vol. 11, Nos. 1-2 
3. The Ascophyllum Zone 
Balanus was abundant in this zone as in the one just above, 
but the most important environmental factor was the Ascophyllum 
which hung in long tufts (fig. 6) from the rocks and gave shelter 
to an abundant fauna. The most characteristic animal which 
grew attached to this alga was Sertularia pumila which covered 
the fronds (fig. 7) in protected situations; in exposed places it 
was largely replaced by the alga, Polysiphonia fastigiata Grev. 
Fig. 6. Showing an Alga-Covered Rock Face at Station 9. 
There is no Fucus except where the tide spurts through a narrow fis- 
sure (/); Ascophyllum (a) replaces it on the protected surfaces. The Bal- 
anus zone (6) is above the Ascophyllum. 
(fig. 8). At the bases of the plants various Bryozoa and Clava 
often formed a coating. 
M any animals found shelter or fed among the fronds of Asco- 
phyllum when the tide was out. Among these Bella, nemerteans, 
nematodes, Carcinides , and amphipods ( Grammarus locusta, G. 
marinus, Allorchestes, Amphithoe) were regular residents. Ophio- 
polis, Hyas, and Strongylocentrotus were each found only once 
and evidently belonged to a deeper stratum. At night and on 
