27 



Description. Fronds coespitosely rise from matted fibres, and are 

 narrow linear, 1-1.5 mm broad, attaining the height of 5— lo cm They 

 divide near base giving rise to many main divisions, and are many 

 times more or less irregularly pinnated in disticho-alternate manner. 

 Main divisions often appear somewhat dichotomoiis and pinnately 

 branched assuming pyramidal outline in some specimens ; or they branch 

 upward with upper branches often elongating and decompounded, and 

 branches reaching an equal height, with the branches very patent, the 

 entire frond is somewhat flabellate in outline. Pinme are linear in 

 outline, very patent, straight and not in-rolled at apex, and taper to a 

 fine point : they are alternate, regularly pinnulated, and are here and 

 there often very stunted and spinose, either pinnulated or naked, being 

 especially so in lower ones of stem and main branches. Pinnula3 are 

 short, subulate and alternate, and younger ones carry fibrilke at apex ; 

 they are mostly simple, but some are pinnated again with pinnellae. 

 Stichidia are transformed from pinnulae being aggregated on a short 

 stunted upper pinnas, and are flabellato-dichotomous ; each is lanceolate, 

 often emarginate at apex, embracing a double row of tetraspores. 

 Cystocarps are unknown, Pericentral cells are 6-8, thickly corticated; 

 midrib is insignificantly visible in wider portion of branches. Color 

 is dark purplish-brown, and the plant stains the paper purplish, on 

 which it is dried. Substance is between membranous and cortilaginous ; 

 and the plant imperfectly adheres to paper in drying. 



Remarks. At first I took the present plant for Rytipliloza com- 

 planata Ag. on account of somewhat close resemblance of external habit ; 

 but when I found that Ry. complanata Ag. is really a species of 

 Polysiphonia, as the character of stichidia proves it to be (J. Agardh's 

 Sp. Alg. II, p. 933), I came to doubt my identification ; for, though my 

 plant has some resemblance to Polysiphonia (Rytiphlosa) complanata J. 

 Ag. in its general aspect, yet it has stichidia bearing a double row of 

 tetraspores. 



On closer examination of those two plants, I found a difference 

 in the mode of ramification and in the structure of the terminal portion 

 of branch. In Polysiphonia complanata J. Ag., (1} on the one hand, the 



W This study has been made from a dried specimen of Rytiphlcea complanata from Biarritz, 

 which is kept in my herbarium. 



