THE BENTHAL 



191 



edge of the continental shelf is called by Murray the great feeding 

 ground of the ocean, to which cod and herring, mackerel and tunny, 

 and even the whales, descend. 



Fig. 29.— Arrangement of animals on 0.25 sq.m. of sea bottom. I, Macoma 

 community, at 0.3 m. depth, exposed at low tide, in the Ringkoebing Fjord. The 

 inhabitants of this area include, among bivalve mollusks, 1 adult and 2 young 

 Mya arenaria; 5 Macoma baltica; and 1 adult and 3 young Cardium edulc; and 

 among annelids 4 Arenicola, 1 Aricia armiger, 2 Nephthys sp. After Petersen. 



Depositing shore faunae. — Although such a general characteriza- 

 tion of the fauna of the sea bottom with loose material may be made, 

 its animal life is not uniform, but changes from locality to locality in a 

 notable way, even on extensive areas where the nature of the sub- 

 stratum and plant growth is essentially uniform. Within this biotope 

 special facies are distinguishable, which are repeated at other points 

 when the same conditions are exactly repeated. A certain regularity 



