BELOW THE TIDEMARK 265 



hang on the rocks of an English cove or float on the steam- 

 ing levels of the Sargasso sea. On the coast their character- 

 istic place is between high and low-water mark, and we can 

 hunt beneath them at low-water for prawns. On rocks 

 above high-water mark, where only the spray dashes in 

 storm, grow the small grey seaweeds that look like lichens, 

 and are closely related to them. But at ebb of the spring 

 tides, when the sea yields us a few yards more of its territory 

 than usual, we may notice that the seaweeds on the lowest 

 rocks are less often bladder-wrack than the smooth, strap- 

 like plants of many shapes which are often known as oar- 

 weed. Oarweeds also grow in the deep rock-pools which 

 form beautiful natural aquaria on the bolder parts of the 

 coast. They are the seaweeds of deeper water, and need no 

 air-bladders to keep them at the surface. Beneath the sea 

 they form immense waving jungles to a great depth, with 

 their own deep-water fauna ; but most of them are still 

 within the power of the upper air. An ordinary breaker is 

 only a superficial ruffle of the sea, and its effect is felt for a 

 depth of a few feet. But when steady gales out on the 

 Atlantic have set in motion a great body of water, the move- 

 ment of the ground-swell is much deeper, and its power often 

 immense. All the boulders and shingle off the shore grind 

 together with a noise which can be heard for miles inland ; 

 and then the oarweed of the deep water gets torn from its 

 hold, and is cast up in huge masses. Coves are sometimes 

 filled with weed to a depth of a yard after a heavy ground- 

 swell, and the stench of the stuff in decay becomes an almost 

 intolerable nuisance in creeks and havens. This green 

 harvest of the sea gives some idea of the extent of the 

 forests of oarweed which fringe our shores ; and a toy 

 picture of their luxuriance is to be seen in many of the deep, 

 warm rock-pools on the coast of Devon. 



