F. Børgesen: List of species. 467 



are formed near the base of the ramuH covering densely several 

 cells. The antheridial stands were first observed by Farlow 

 who in "The Marine Algæ of New England", p. 140, pi. X, fig. 1 

 has described and figured them. 



Tetrasporangia, cystocarps and antheridia were found in 

 the months January to March. 



106. Spyridia clavata Kiitz. 



107. — aculeata (Schimp.) Kütz. • 



var. ty pica. 

 I var. disticha Borgs. 



f. inermis Borgs. 



108. Centroceras clavulatum (Ag.) Kiitz. 



109. Ceramium fastigiatum (Roth) Harv. 



110. — strictum Grev. et Harv. 



111. — transversale Coll. et Herv. 



112. — nitens (Ag.) J. Ag. 



113. Laurencia Poitei (Lamx.) Howe. 



114. — papulosa (Forsk.) Grev. 



115. — obtusa (Huds.) Lamx. 



var. gelatinosa (Desf.) J. Ag. 



116. — implicata J. Ag. 



117. — chondrioides Borgs. 



118. — cervicornis Harv. 



119. Chondria polyrliiza Coll. et Herv. 



The first time I examined this plant I had only a dried spe- 

 cimen at my disposal, now I have come across some more material, 

 some of it preserved in alcohol. 



In this material the group of rhizoids were not so very abund- 

 ant, being mostly restricted to the basal parts of the filaments 

 or to filaments becoming decumbent or approaching other algæ 

 etc. to which they could fix themselves. 



A transverse section shows that the thallus is terete (Fig. 

 426 6), and that the cells have very thin walls. The small central 

 cell is surrounded by four to six large pericentral cells; at the' 

 periphery these have, for the most part, some smaller cells, the 

 whole being encircled by a thin cortical layer of quite small 

 cells. 



The branches have rather broad bases (Fig. 426 a), these 



30* 



