HOW TO KNOW THE SEAWEEDS 



106b Thallus inflexible, hard and stony throughout.. Fig. 143 107 



Figure 143 



Fig. 143. Lithothamnium giganteum L. R. Mason 



An entire plant, X 1.2. This species from southern Cahfornia is 

 an example of a crustose coralline in which prominent excrescences 

 are produced and in which growth may proceed as the plant, having 

 originated on a loose pebble or piece of shell, is tossed about in the 

 surf or rolls along the sea floor. Numerous other species grow firmly 

 attached to rocks and may have such surface outgrowths or may be 

 only warty or entirely smooth. This range of characters is common 

 also to the genera Lithophyllum and Goniolithon in which generic dis- 

 tinctions are based upon internal anatomy and reproduction. Although 

 species of Lithophyllum and Lithothamnium may be found along either 

 the Atlantic or Pacific coasts, Goniolithon is as yet recorded from the 

 United States only in the warm waters of Florida. 



Ill 



