PHAOPHYCEA 83 
Fic. 17.—a, transverse section of leaf of Postelsia, showing furrows; b, 
transverse section of furrow with sporangia ; ¢, sporangia and paraphyses ; 
d, transverse section of frond of Macrocystis; e, transverse section of a 
furrow with sporangia ; f, sporangia and parphyses. Variously magnified. 
(After A. L. Smith and F, G, Whitting, in Phyc, Mem.) 
G2 
