74 



sections, sometimes showing less diameter than from the surface 

 or the roof. 



The conceptacles of cystocarps and antheridia are not yet 

 known in any of the forms. 



In both the forms the conceptacles of sporangia finally grow 

 down into the frond. Overgrown ones are partly rather numerous, 

 partly very few in number, sometimes even not to be found. Only 

 the central portion of the roof gets dissolved, not seldom though 

 the whole roof and then it partly leaves a nearly cup-shaped partly 

 a deeper scar. Such scars become effaced by local formations of 

 tissue, which, if the scars are not too shallow, rather often are 

 covered by a new thickening layer of the frond and to be seen 

 on a section. 



Remark on the synonomy. Among some Greenlandic speci- 

 mens from Julianehaab referred by Rosenvinge to L. soriferum 

 (L. tophiforme) is a couple provided with conceptacles of sporangia. 

 These in my opinion really belong to the present species and are 

 closely related to f. Gfranii. I found overgrown conceptacles of 

 sporangia or such ones filled with new-formed tissue, which is 

 never due to L. tophiforme. In the superficial conceptacles, coin- 

 ciding with those of the present species, I also found some few 

 bisporic sporangia, which appeared to be mature. Besides, the 

 specimens differ from L. tophiforme by a little thinner branches, 

 shorter axes and somewhat uneven surface, but on the other hand 

 the limits are in this respect often difficult to draw. A couple of 

 others I suppose to be identic with the last named species. 



Relation to other species. With regard to the sporangia the 

 present plant is most nearly related to L. glaciale, but otherwise 

 it is quite different and cannot be confounded with this species 

 except young individuals. It in some respects shows greater affinity 

 to the following species, L. colliculosum. On the other hand it 

 may without closer examination be confounded with certain forms 

 of L. fruticulosum, as f. curvirostra. However, it is most easily 

 confounded with L. tophiforme, and sterile specimens sometimes 

 are difficult to distinguish from smaller and thinner forms of the 

 latter, although typically developed or fertile specimens are sepa- 



