— 145 - 



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

 Myrionema globosum (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 unbranched 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 thickness of these filaments is 

 about 7 a. Well developed rhizoids are frequently occurring and grow in- 

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

 of the frond consists for the most part of plurilocular sporangia, 5,8 — 7 



K 



e 



Fig. 4. Myrionema Corunnœ Sauv. var. filamentosa. 

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



a a horizontal filament with rhizoids and an assimilative filament; b branched 

 horizontal filaments, c fragment of a horizontal filament with a hair enclosed 

 in a sheath below; d fragment of horizontal filament with a rhizoid, young- 

 filaments and plurilocular sporangia; e fragment of horizontal filament with 

 two rhizoids and a plurilocular sporangium. 



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

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

 branched sporangia. The assimilative filaments I have found much more 

 rare (than the sporangia), they are 5,8 fi thick and nearly of the 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 Gorunnæ 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. 



