﻿Study of the Animal Ecology of the Shore. 231 



The depth at the lower limit of Zone 3 was about 10 feet. 

 Our Zone 4 was only 6 feet in extent from Zone 3 to low- 

 water mark. It was thickly overgrown with Lo.minarm. 



Positions. — The following positions were recognised : — 



1. Upper surface of stones. 



2. Beneath stones not imbedded. 



3. In substratum,^ and reached by digging. 



4. On or amongst different kinds of weed. 



E.g., in Zone 1. Fucus platy carpus. 



„ Pelvetia canaliculata. 



„ Enteromorpha intestinalis. 



Zone 2. Ascophylluni nodosum^ Base. 

 „ Ascophyllum nodosum, Branches. 



Fucus iplaty carpus. 



Zone 3. Fucus serratus. 

 „ Chondrus crispus. 



„ Cladophora rupestris. 



Zone 4. Laminaria, Branches. 



„ Laminaria, Base. , 



„ Fucus serratus. 



„ Chondrus crispus. 



„ Cladophora rupestris. 



Drift (f.w.). Enteromorpha intestinalis. 



Fresh- Water Area. — In every zone except Zone 4 an area 

 over which fresh water trickled could be recognised. These 

 zones were therefore divided up into a fresh-water portion, 

 and a portion not exposed to action of fresh water at low 

 tide. Zone 1, lower, was throughout its extent exposed to 

 fresh water, owing to the presence of a small stream at the 

 northern corner of the bay. In fact the fresh water 

 percolated all over the bay with the exception of an area 

 (in Zones 2 and 3) in the southern part of the bay, from 



^ This position can be subdivided according to the nature of the substratum, 

 e.g., shell gravel, sand, mud, etc. 



^ It has been necessary to distinguish as separate positions, hose, and 

 tranches, since each has a typical fauna. 



