i] THE CATEGORIES OF LIFE 3 



small fishes such as the blennies, gobies, and gunnells ; 

 many Crustacea such as lobsters, crabs, hermit-crabs, 

 and prawns; molluscs such as the whelks, horse- 

 mussels, clams, scallops, and brightly coloured sea- 

 snails (Nudibranchs) ; starfishes, sea-urchins and 

 brittle stars ; many kinds of crawling worms ; sea- 

 anemones, sponges, and numerous species of plant-like 

 zoophytes and polyzoa encrusting or growing on the 

 stones or larger algae. This fauna and flora inhabiting 

 the zone of shore only exposed by exceptional ebb- 

 tides we may call the Laminarian Benthos. If our 

 initial point of departure had been a rocky coast we 

 should still find much the same distinction, for the 

 upper parts of the rocks would be covered with the 

 barnacles, periwinkles, etc., while the lower rock-pools 

 would contain much the same organisms as we found 

 on the lower parts of the gravelly beach. If we had 

 started from a flat, sandy shore the nature of the 

 life would, however, be quite different, for the sand 

 between the tide marks would probably contain such 

 molluscs as the cockle, animals like the lugworm 

 burrowing beneath the surface, and small Crustacea 

 such as the Copepods. The larger rooted algae would 

 be absent, but their place would be taken by micro- 

 scopic plant life. Here and there on the surface of 

 the sand, on the ripple marks, or in the little gutters 

 left by the retreating tide there might be patches of 

 yellow-green slime, and on examining these we should 



12 



