422 
together, one sporangium springing from every cell, but sometimes 
vegetative cells intervene. The sporangia are divided not only by 
transverse walls, but also by more or less oblique longitudinal 
walls. As the sporangia gradually arise along the filament a pe¬ 
culiar development takes place, viz. the cells whence the sporangia 
spring divide and turn into sporangia, transforming the whole of 
the sporangia-bearing portion of the erect filament into what may 
be termed a single, large plurilocular sporangium. The latter generally 
ripens and is emptied successively from the apex downwards to 
the base, though not always, for, as shown in fig. 78, c specimens 
occur in which some of the sporangia are emptied here and there 
along the filaments, and most commonly the cells whence these 
sporangia spring are emptied simultaneously. The plurilocular 
sporangia are about 11 y broad and 40 y long. I have only found 
a small quantity of unilocular sporangia (fig. 78, d); the latter 
vary somewhat in shape being obovate or nearly so and they 
sometimes form a sporangium in connection with the cell whence 
they spring, and sometimes are separated from this cell by a wall. 
Besides the sporangia, the erect filaments bear now and then true 
Phseospore-hairs which grow endogenously and have a distinct 
sheath as indicated by Sauvageau, 1. c. p. 47. These hairs are 
usually lateral and I have only rarely come across terminal ones 
such as are shown in fig. 78, a. The hairs are about 6—7 y thick; 
as I said before they do not occur on all the erect filaments. 
Besides long branches, quite short sporangia-bearing branchlets 
with only one vegetative cell are occasionally met with as, e. g. 
shown in fig. 78, f. 
The chromatophores consist of a parietal, irregularly branched 
or perforated plate (fig. 78, e). 
This plant was found on the conceptacles of Himanthalia lorea, 
where it occurred as a short, dense mat, often associated with 
Myrionema globosum. 
A species which appears to me to be most closely allied to M. 
speciosum is M. globosum though the latter differs considerably from 
the former, more particularly, e. g. in the different ramification of its 
erect filaments as also in the form and position of its sporangia. 
Myrionema speciosum somewhat resembles the Ectocarpus tomen- 
tosoides var. norvegica Gran 1 , which is fully described and figured 
1 Gran, H. H.: En norsk form af Ectocarpus tomentosoides Farlow (i Chri¬ 
stiania Vidensk. Selsk. Forhandlinger for 1893. No. 17). 
