166 



The free filaments of the plants on Scytosiphon and Chorda grow 

 both horizontally on the surface of the sorus and inwards parallel to the 

 paraphyses and sporangia, but I have never seen them penetrate the cell- 

 walls of the inner cortical layer; on Scytosiphon I found them not rarely 

 united in a pseudoparenchyma. The specimens growing on Chorda had 

 usually more regularly shaped cells in the horizontal filaments than in 

 the filaments growing inwards. The cells of the latter were usually 

 barrel- shaped, approximately isodiametric or twice as long as broad; the 

 end-cell is always narrower and comparatively longer than the other cells 

 and tapering towards the apex. Sometimes I have found the sporangia 

 and the hairs apparently terminal on the filaments growing inwards, and 



such is the case when the connection 

 between the inwards growing and 

 the horizontally growing parts of the 

 filaments is loosened. The specimens 

 growing on Chorda tomentosa have a 

 close resemblance to Phceostromasequale 

 (Oltm.) Kuck., but I have referred them 

 to P. pustulosum, as they substantially 

 agree well with the description of this 

 species (Kuck. 1. c.) ; on the other hand 

 I think that Phaeostroma gequale will 

 not turn out to be specifically distinct 

 from P. pustulosum (cfr. Kuck. Bemerk. 

 II, p. 385). The specimens growing on 

 Laminaria agree with the Greenlandic 

 plants on Laminaria mentioned by 

 Rosenvinge (1. c. tig. 15), and viewed 

 from above they precisely resemble 



Fig. 21. 



Ph(Costroma pustulosum Kuck. 



a a vertical filament with terminal 



hair: b vertical filament with young Kuckuck's fig. 2 in Tab. VII (1. c). 



lateral hair; e, d vertical filaments 



with terminal plurilocular sporangia 



in different stages of development. 



(31(J:1.) 



The hairs of the Icelandic specimens 



fully agree with Rosenvinge's description 



(1. c.) of the hairs of the Greenlandic 



plants, having always very long basal 



cells, somewhat narrower and more thick-walled below. The growing 



point of the hair is always situated above the basal cell. 



The species had plurilocular sporangia in May — July. 



E. I eel. Holraanes, in Scytosiphon. 



NW. Icel. Latravik in A(5alvik (CO.), in Phyhitis ; Bfldudalur, in 

 Laminaria saccharina. 



SW. Icel. Stykkisholmur, in Chorda tomentosa and Laminaria sac- 

 charina f. phyllitis. 



