﻿Study of the Animal Ecology of the Shore. 



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II. Description of the Experiment. 



The Area Chosen was a small bay on the east side of 

 Cumbrae facing Fairlie, and lying in the sheltered channel 

 between the island and the mainland, protected from the 

 prevailing winds both from the south-west and from the 

 east. The aspect was, roughly, east by south-east. 



Extent of the Bay. — At its landward limit, i.e., where 

 bounded by a grass-covered bank, the breadth was 50 feet. • 

 At low-water mark, ordinary tides, the breadth was about 

 100 feet. The shore sloped gradually from the upper to the 

 lower limit indicated, the fall being roughly 1 in 7'5. The 

 distance from high-water mark to low-water mark was 

 80 feet. 



Nature of the Shore. — At its north and south limits, the 

 bay was bounded by rocks, red sandstone of Carboniferous 

 age. 



The shore was covered by shelly sand and gravel, overlying 

 rock similar to that of the boundaries and found at a depth 

 of a few inches to a foot below the surface. This surface 

 was covered, over almost the whole area, by loose stones, 

 varying in size from 9 to 18 inches in diameter, flattened, 

 and having a rough surface ; occasional boulders occurred of 

 larger size. 



At the southern corner of the top part of the area a stream 

 of fresh water could be traced by the presence of a growth of 

 green weed, Enteromorpha intestinalis, spreading out in 

 triangular form from above high-water mark. The fresh 

 water, percolating through the gravel, was found to pass 

 down in a straight course from its entrance, spreading out 

 as it passed on towards low water, but diverted from the 

 southern portion of the bay, in its lower part, by projection 

 of the bounding rocks, at a distance of 24 to 28 feet from 

 high-water mark. 



Zones. — The zoning was according to depth. The nature 

 of the seaweeds was taken as a rough guide for the de- 

 limitation of the zones, and the following were distinguished : 

 Zone 1, extending 24 feet downwards, characterised by the 

 occurrence of Fucus platycarpus and Pelvetia canaliculata ; 



