No. 3] REMARKS ON NORTHERN LITHOTHAMNIA, 61 



This species is very nearly related to L. tophi for me f. gh- 

 bosa, and it seems doubtful whether the alga ought to be con- 

 sidered as an independent species. However, it is distinguished 

 by its branches being of almost equal thickness throughout, whereas 

 in the said species they are usually thicker or more coalescing in 

 the central parts. Besides, the conceptacles, particularly those of 

 cystocarps, are usually smaller. In specimens typically developed 

 the branches are 1,5 — 2 mm. thick, partly rather crowded, partly 

 more or less distant, in the latter case generally with numereous 

 short lateral branches as in similar specimens of L. topliiforme, 

 or forming almost obpyramidate branch-systems, but less distinct 

 than in f. spluerica of the said species. Other specimens with 

 branches about 2,5 mm. thick are in habit hardly distinguishable 

 from the form last named. Sometimes the branches form rather 

 irregular bundles and then approach certain forms of L. nodulo- 

 sum in habit. Moreover, there are specimens with the branches 

 densely crowded and almost destitute of lateral-branches. Such 

 specimens, which partly occur in other localities than the former 

 ones, are in habit almost fully resembling small nodules of L. 

 fornicatum f. sphcerica and partly even f. dimorpha. 



The conceptacles of sporangia are scattered or crowded in 

 the outer branches, finally subprominent, 300—400//. in diameter; 

 the sporangia are bisporic, 90 — 140, by 40— 60 p.. Also the cysto- 

 carpic conceptacles are 300 — 400 p- in diameter, conical and re- 

 sembling those of L. topliiforme, but usually smaller. I have not 

 seen conceptacles overgrown in a number of specimens examined. 



The species appears in a depth of 1 — 15 fathoms in places 

 sheltered with tides strongly running. It bears reproductive organs 

 in the months of July— September. 



Area: Norway: Vardo 1 ), Mjaanes in Altenf jord(!), Svolvaer 

 and Balstad in Lofoten (!), Frooeme and Froien(!) 2 ) 



1 ) Only dead specimens in company with other species brought up by exca- 

 vators in the harbour. 



2 ) Among a number of specimens from these two places only a single one bears 

 a few conceptacles of sporangia. They are coarser than specimens typi- 

 cally developed and perhaps belong to L. topliiforme, though as to rami- 

 fication more agreeing with the species in question. 



