1922] Setchell-Gardner : Phijcological Contributions 363 



fifteen cells long. At times sessile forms are to be found on the erect 

 filaments about two-thirds of the way up to the apex, but more gener- 

 ally they are terminal on small lateral ramuli on the erect filaments 

 arising from the middle to near the apices. Rarely there are small 

 lateral forms on the ramuli. Finally, they may rarely be terminal or 

 intercalary and seriate on the erect filaments although the erect 

 filaments are usually piliferous. The terminal forms on pedicels, and 

 particularly on the main erect filaments, are often quite blunt, even 

 clavate. Others on the prostrate filaments are narrow and sharply 

 attenuated, at times terminated by a sterile pointed filament, in effect 

 intercalary. Many of the gametangia, terminal on the ramuli, are 

 composed of a single series of loculi. Most of the others are two or 

 more seriate. The hair filaments do not seem to be abundant. They 

 arise laterally on the main filaments, usually above the center. The 

 meristem in these hairs is at the base which is surrounded by a sheath 

 similar to that described by Sauvageau (1897, p. 47) for Myrionema. 

 The ramuli are decidedly curved upwards. 



The species is similar to Myrionema speciosum from the Faeroes, 

 described by Borgesen (1902, p. 421). Our plant is more slender in 

 all of its parts, has much longer gametangia, and possesses, in addition 

 to the sessile, secund gametangia figured by Borgesen, occasional inter- 

 calary ones and many terminal ones on the numerous clustered ramuli. 

 These ramuli are in turn occasionally branched, usually arise in 

 groups, sometimes whorled, two or three arising from the same cell, in 

 other instances they are secund. 



TliQ species often grows in association with other members of the 

 Myrionemataceae and the Ectocarpaceae. As a rule, the main erect 

 filaments do not enter into the formation of gametangia, but give rise 

 either to sessile gametangia or to the ramuli. No zoospores have been 

 observed in the so-called zoosporangia. We suspect that these may 

 represent pathological conditions. 



Compsonema serpens sp. nov. 



Plate 39, figure 7 



Frondibus stratum plus minusve expansum in superficie hospitis 

 formantibus; parte repente filamentis multo contortis, irregulariter 

 ramosis composita ; filamentis erectis simplicibus aut raro superne 

 ramis paucis subulatis indutis, interne leviter attenuatis, superne 

 gradatim attenuatis, non piliferis, 375-425/i, longis; pilis veris deunt- 

 ibus; cellulis filamentorum repentium cylindricis ad dissepimenta 

 usque ad irregularibus, 10-13/* diam., 0.5-3-plo pongioribus; cellulis 



