200 IP o 5 t e 1 £5 i a 



lamina. This is the condition in Lam- 

 inaria, Nereocystis and other genera. 

 In Pterygophora sori do not occur upon 

 the central lamina, but only upon the 

 lateral pinnae, while in Alaria and Egre- 

 gia special outgrowths of the stipe known 

 as sporophylls are produced, and these 

 are covered by the sori. In Pleuro- 

 phycus the soral area is limited to the 

 midrib of the lamina. 



In color the kelps are for the most 

 part a rich olive-green. Deeply sub- 

 merged portions are commonly of a 

 lighter tint, as may be seen in the 

 holdfasts of Nereocystis. Stipes are 

 often darker and those of Pterygophora 

 are almost black. Soral patches are 

 frequently of a darker color, sometimes 

 approaching chocolate -brown, and may 

 easily be recognized by this character. 

 The lamina itself is much darker in 

 some varieties than in others. Thus 



