Smithsonian Report, 1915.— Walcott. 



Plate 5. 



Microscopic Cells from Recent Blue-Green Alg/e and Their Algonkian 

 Representatives. 



Figs. 1 to 6a are from the ancient forms Xcwlandia and Caniai^ia; figs. 7 to Sa are from the recent 



Blue-Gtpeu Algse. 



