THE ALGAE OF BERMUDA. 93 



three or four cm. from the base, descending, terete, branching fihi- 

 ments, of an average diam. of one half mm., forming a loose felt. A 

 cross section shows a densely cellular structure, the cells much smaller 

 than in the median layer of the frond, the superficial cells much like 

 those of the frond. From the superficial cells issue, not continuously 

 but in groups, monosiphonous filaments, 20-25 yu diam., the cells 2-4 

 diam. long, nodes somewhat constricted; these filaments are mostly 

 simple, occasionally with short branches ; when a filament reaches the 

 substratum the terminal cell forms a coralloid expansion as an organ 

 of attachment. Other species of Dictyota, D. ciliaia for instance, are 

 attached by rhizoidal filaments of a similar character, but arising 

 directly from the frond; D. dcntafa is the only Bermuda species in 

 which they arise from descending cellular branches. In older plants 

 prolifications are common from the surface of the frond, sometimes 

 papillose to clavate, sometimes flattened with rounded outline. 

 None were observed over 1 mm. in length; the papillose-clavate 

 form seemed to be of a similar character to the descending filaments 

 developed near the base. Antheridia were common in material col- 

 lected in Jan., July and Aug.; no other fruit was observed. 



DiLOPHUS J. G. Agardh. 



D. GUiNEENSis (Kiitz.) J. G. Agardh, 1880, p. 108; Vickers, 1905, 

 p. 59; 1908, part 2, p. 37, PI. IX; Borgesen, 1914, p. 214, figs. 164- 

 165; P. B.-A., No. 2080; Spatoglossum guineense Kiitzing, 1843, p. 339; 

 1859, PI. XLVI, fig. I. South Shore near Paget, Farlow; Gravelly 

 Ba\-, March, Hervey. 



