71 



FIG. 11. SpJaclinidtum riigoum Grev. a, plant reduced one-half, b, sec- 

 tion through apex, showing apical cell, c, section through young conceptacle. 

 d, conceptacle with sporangia, e, section through branch. /, early stages in 

 the development conceptacles, showing four initial cells, g, further -stage in 

 development of conceptacle. h, transverse section of thallus. J to h much, 

 magnified. (After M- 0. Mitchell and f. G, Whitting, in Phyc. Mem.) 



