1917 



Muenscher; Key to Phaeophyceae 



275 



1. Fucus EVANESCENs Agardli Sp. 1. p. 92. (Farlow, Algae of New 



England, p. 101.) 



Fig. 37 



Plant repeatedly dichtomously branched, several dm. long; branches 

 with distinct midrib below, wider and scarcely visible above, margin 

 broad, entire, somewhat wavv ; bladders usualW wanting; receptacles 

 swollen, broad, usually united in pairs, sometimes with a small margin 

 along the edges. 



Very common in the littoral zone. The wider typical forms are most 

 common but in certain places forms with narrow branches are ratlier 

 frequent. 



2. Fucus iNFLATUs (L.) Vahl Fl. dan. tab. 1127. Fig. 38 



Plant regularly dichotomously branched, three to nine dm. long; 



branches with a distinct midrib below, invisible above, margin wanting 



or when present very narrow and smooth; bladders usually wanting. 



Fucus 

 evanescens 



Fucus Pelvetiopsis Pelvetia 



inflatus limitata fastigiata 



PLATE 62 



Fig. 37. a, Portion of branch with receptacles ; b, diagram of cross 

 section through a receptacle ; X 0.33. c. Diagram of vertical section of 

 oogonium ; X about 300. 



Fig. 38. a, Portion of branch with receptacles ; b, diagram of cross 

 section through a receptacle. X 0.33. 



Fig. 39. Portion of branch with receptacles. X 0.33. 



Fig. 40. Diagram of vertical section of oogonium. X about 300. 



