145 



The species is nearly related to Myrionenia balticum (Rke.) and 

 Myrionema globosiim (Rke.) but differs from the former by the condition 

 of the margin of the basal disc, the branched and the sessile sporangia, 

 from the latter chiefly by the iinbranched assimilative filaments. 



var. filamentosa nov. var. 



The basal portion of the frond consists of free horizontal filaments, 

 irregularly branched and creeping between the apices of the sporangia and 

 paraphyses of Laminaria hyperborea; the tliickness of these filaments is 

 about 1 11. Well developed rhizuids are frequently occurring and grow in- 

 wards between the parajjliyses and sporangia of the sorus. The erect portion 

 of tlie frond consists for the most part of pliii'ilociilar sporangia, 5,8 -7// 



Fig. 4. Myrionema CorunncB Sauv. var. filamentosa. 



a, b, d, e 316 : 1. r 550: 1. 



a a horizontal filament with rliizoids and an assimilative filament: b l)rancheil 

 horizontal filaments, c fraijment of a horizontal filament with a liair enclosed 

 in a sheath below: d fragment of horizontal filament with a rhizoid, vounj,' 

 filaments and pliuilucular sporangia; e tVagnient of horizontal filament with 

 two rhizoids and a plurilocular sporangium. 



broad and 30 — 44/i long, consisting of a single series of loculi; they are 

 usually sessile and simple and I have hut seldom met with stalked or 

 branched sporangia. The assimilative filaments I have found nmch more 

 rare (than the sporangia), they are 5,8 fx thick and nearly of tlie same 

 length as the sporangia. I have only met with basal hairs, and these 

 were enclosed in a short sheath below. The hairs are rare. As far as 

 I can see in my alcohol material there is only one chromatophore in each 

 cell. The unilocular sporangia are unknown. 



This variety differs chiefly from the typical Myrionema Gorunnaj in 

 the condition of the basal portion; I have sometimes met with specimens 

 of the typical form, with the margin of the basal disc partly consisting 

 of free, creeping filaments fully agreeing with those of the variety. 



