68 NEW ZEALAND PLANTS. 



Where rocks jut out into the sea, forming pools, there the beau- 

 tiful red seaweeds have their home ; but where the sea dashes with 

 fury, the huge brown ones are found. As two of these are so frequently 

 cast up on the shore, they, at any rate, must be known to most who 

 aie acquainted with the seaside. The one (Macrocystis Diibenii) 

 grows to an immense size, and its leaves float upon the surface of the 

 sea by means of their small bladders full of air, while, dozens of feet 

 below, the cord-like stems are anchored firmly to the rocky floor of the 

 ocean. The other (D'UrviUaea utilis) is found in rougher water, its 

 stouter stem showing a honeycomb-like structure when cut into. 

 UVrvillaea gets its name from the Admiral D'Urville mentioned in 

 Chapter II. By the Stewart Island Maoris its " leaves ' are made 

 into bags for holding the preserved mutton-birds. 



In the calm waters of the West Coast Sounds, where not too deep, 

 are flower-gardens of the sea, whose loveliness can be seen for con- 

 siderable depths through the transparent water. Generally speaking, 

 the depth of water determines the distribution of seaweeds. Thus 

 the green ones are found in the shallowest pools, and the red in the 

 deepest, while the brown occupy a position midway, and some of these 

 may be seen writhing like snakes over the glistening rocks at low 

 water (fig. 2). Some seaweeds behave like the perching-plants of the 

 forest, and have taken up their abode on other species. 



SANDHILLS. 



On many parts of the coast, sand is continually being brought on 

 to the shore by the advancing waves. In the neighbourhood of high- 

 water mark the shore soon becomes dry, and the sand is then borne 

 landw r aids by any wind coming from the sea. Where the sand 

 accumulates faster than it is blown away, a hill, or dune as it 

 is frequently called, is formed. Any obstacle in the path of the blown 

 sand will also arrest its progress and cause its heaping-up. The 

 dunes of New Zealand are of great extent, and occupy an area of more 

 than three hundred thousand acres. In some parts of the coast the 

 belt of dunes is more than six miles in width, and in the north of the 

 Auckland Province, on the west of Stewart Island, and elsewhere the 

 sandhills attain a height of several hundred feet, though usually they 

 are much lower. 



Frequently the dunes are very unstable, and in some places so 

 much so that great areas of moving sand exist. These i; wandering 



