HOW TO KNOW THE SEAWEEDS 



145a Thallus usually under 20 cm. tall, greenish, spongy. Fig. 185.... 

 AvTainvillea 



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Figure 185 



Fig. 185. Avrainvillea sp. 



An entire plant to show the flabellate form of the spongy thallus, 

 X 1. Several species may be found in quiet, shallow water on sandy 

 or muddy bottoms in southern Florida. They are not particularly 

 abundant, nor are the dark, often silt covered blades attractive. The 

 spongy thallus is made up of branched, interlaced filaments which 

 provide certain diagnostic characters for distinguishing species. 



145b Thallus large, usually over 20 cm. tall, coarse, brown, firm. . . . 146 



142 



