4 
winds, thus protectingit from the full force of the worst gales. 
It is, however, fully exposed to such gales as come up from 
the south-east, gales whose violence is clearly illustrated 
by the tons of algal vegetation carted from the Castletown 
shore in the autumn. 
In making the survey careful notes have been kept not 
only of the species found in the area, but also of the time 
of occurrence, the zone of distribution and the period of 
reproduction in each case. 
In the present Memoir no attempt has been made to give 
an ecological account of the vegetation. That is reserved 
for the future. Some attention has, however, been paid 
to a tentative enquiry into the factors governing algal 
migrations from level to level on the shore throughout 
the year. A full and detailed study of the ecology of the 
area will be the subject of a later paper. Meantime the 
immediate object of publication is to provide the student- 
visitor to the area with a guide that will, it is hoped, 
facilitate his efforts to make acquaintance with the algal 
flora and to gather some understanding of its variation 
from one season to another. 
THE AREA 
In this section no attempt has been made to give an 
exhaustive list of the species to be found in each area. 
Information on the exact distribution of each species is 
given in the systematic list. These notes are intended 
to give the student who has had little previous experience 
directions as to the best part of the area to study, and to 
suggest the commoner genera and species that he might 
reasonably be expected to recognise. 
Port Erin Bay. 
Port Erin Bay offers considerable variety of algal 
habitat. One of the most productive areas lies amongst 
