THE A.LGAE OF BERMUDA. L23 



Polysiphonia Greville. 



1. Pericentral cells 4. 2. 



1. Pericentral cells more than l. 1. 



2. Forming Low, dense, more or less even-topped tufts or mats. 



2. I*. macrocarpa. 



2. Taller, more open in growth. 3. 



3. Segments seldom over 1 diam. long; tetraspores in densely forking, 



divaricate ramuli. 1. P. ferulacea. 



3. Segments in main axis usually over 1 diam. long; tetraspores near tips 



of normal branches. 1. P. havanensis. 



4. Pericentral cells 8-13; soft and dense. 3. P. foetidissima. 



4. Pericentral cells 20-24 in main axis; firmer. 5. P. opaca. 



1. P. havanensis Montagne forma mucosa J. G. Agardh, ksb3, 

 p. 960; P. B.-A., No. 1941; P. havanensis Harvey, 1853, p. 34. 

 Spanish Rock, April, floating by Causeway, Oct., Inlet, Oct., St. 

 George's Bay, Dec, Hervey. On Penicittus, Halimeda, Sargassum 

 etc.; cystocarps in April. Fairyland, Dec, Collins. The fine soft 

 filaments and rich red-brown color are characteristic of this form; 

 the segments vary from one to four diam. long in the same plant. 

 The cystocarps are globose below, broadly urceolate above. The 

 leaves are long and much branched; normal branches are formed in 

 their axils. 



2. P. macrocarpa Harvey in Mackay, 1836, part 2, p. 206; 

 P. B.-A., No. 2093; P. pulvinata Harvey, 1*846-51, PI. CIL B, not of 

 J. Ag. On mangroves, with Dichotomosiphon pusillus etc., Hungry 

 Bay, May, Collins. Forming a close and rather dense coating. The 

 filaments resemble P. subtilissima Mont., but are more slender, and 

 the habit is quite different. An account of the distinction between 

 this plant and the original P. pulvinata (Roth) J. Ag. will be found in 

 Bornet, 1892, p. 306. Our plant is more slender than the European 

 but otherwise the same. 



3. P. foetidissima Cocks in Bornet, 1892, p. 314; British Sea- 

 weeds, No. 29; P. B.-A., No. 1890. On timbers by sea wall at Hamil- 

 ton, Jan., on stones on beach at St. George's, April, Hervey; cysto- 

 carps and tetraspores in Jan. An apparently little known species, 

 but quite well marked. The filaments have 8-10, rarely to L3 peri- 

 central cells, are creeping at the base, then erect, much branched, 

 reaching a height of 15 cm. The substance is soft, the color deep 

 purplish red. It decays promptly when taken from the water, and 

 then thoroughly justifies its specific name. 



