Smithsonian Report. 1935.— Meier 



PLATE 2 



1. The Stones of the old Roman aqueduct, known 

 as the Bridge of the Devil, in Tarragona, Spain, 

 are spotted with patches of aerial alaae. 



Courtesy of Dorothy Meier. 



2 Visible and microscopic algae grow on the 

 stones and in the waters of brooks in the spring 

 and sum.mer. 



Courtesy New York Zoological Society. 



3. Microscopic algae growing on the hairs of the three-toed sloth make it bright green in color. 



