49 



then often resembles emptied conceptacles of sporangia, later as 

 a rule the whole roof. The conceptacles are in a median section 

 internally about 300 p in diameter at the base and about 100 p 

 high. The carpospores appear to be much varying, about 85 p 

 long and 35 p broad. 



The organs that I suppose to be conceptacles of antheridia 

 fully resemble the cystocarpic conceptacles in shape, and occur in 

 the same individual bearing the latter. They are 250 — 300 p in 

 diameter at the base and up to 200 p high. In a median section 

 I found them to be about 230 p in diameter at the base and 80 

 p high, and also here the upper and thicker portion at least som e 

 times falls away. I have not seen the spermatia. 



Relation to other species. It in some sespects stands near to 

 L. dimorphum, and younger individuals, or not opened ones may 

 easily be confounded with that species. It is, however, separated 

 by its branches being in general thinner and less regular, and the 

 ends seldom or not at all truncate, being a much larger plant. 

 Besides, it differs with reference to the development of the frond, 

 as well as the conceptacles of sporangia. The species may also 

 be confounded with certain forms of L. fruticulosum, and in habit 

 sometimes rather resembling the form fastigiata of that species. 

 This, however, is only due to younger individuals. Older or cup- 

 shaped ones are quite different, and merely showing closer affinity 

 to L. fomicatum, from which it is separated by its thinner branches, 

 coarser structure, frequently larger conceptacles of sporangia and 

 apparently different cystocarpic conceptacles. 



Habitat. The species grows in the uppermost part of the 

 sublitoral region on a depth of 1 — 4 fathom, on stony and some- 

 what clayish bottom. It apparently prefers places with rather rapid 

 tides. The very greatest number of specimens collected in July 

 were sterile, some few ones partly scantily, partly more richly 

 furnished with conceptacles of sporangia, some of which were 

 emptied and others with ripe sporangia. Other specimens taken 

 in July and August were richly provided with conceptacles of cy- 

 stocarps and probably also antheridia, partly emptied and partly in 



