A FEW MORE MOLLUSKS. 



our last walk we noticed some 

 of the mollusks which are found 

 living upon the rocks. In many 

 places the seaweeds live there 

 too, and when the tide is out you 

 can see great patches of olive- 

 green vegetation almost entirely 

 covering the hard, gray rocks. 

 The name of the most common of these plants 

 is Fucus, and of this there are several species. 

 Most of them contain little air-sacks near their 

 tips, which act as floats, and assist in keeping them 

 erect when the water is over them. But when the 

 tide is low, you find them lying flat on the sur- 

 face of the rock, or hanging limp from its sides. 



These seaweeds are very 

 ancient plants, and were 

 growing in the ocean long 

 before there were any trees 

 upon the land. They do a 

 vast amount of good, puri- 

 fying the water and giving 



103 



REFERENCE TOPICS. 



Plants -without flowers. 

 "Sea-cradles." 

 Purple dye. 

 What Is varnish 

 Uses of borers. 

 Our advantages. 



