133 



the upper thickening layers are after decalcifying easily separated 

 by pressure. 



Remark on the synonomy. Accordtng to kindly communica- 

 tion of Prof. Farlow he considers his L. polymorphum to be 

 most nearly related to L. compactum. On the same substratum 

 as a specimen of his L. fasciculatum, mentioned under L. colli- 

 culosum, I found a small crust with sporangia in development, 

 which belongs to the present spedes, and the named plant most 

 probably at least in the main includes L. compactum. Besides, I 

 got a well developed, sporangia-bearing specimen from Mr. Collins, 

 which also is identic with this spedes. Pl. 19, fig. 4. Collins' 

 coil. 2136. „Eagle Island, Maine. Apparently thrown up from 

 deep water". 



I cannot agree with' Ko Ider up Ros en vinge, that his L. 

 circumscriptum ft validum belongs to the spedes, to which it is 

 referred by him. He had the kindness to send me specimens of 

 this form, and, in my opinion, it is not a form of L. circumscriptum, 

 but accords well with L. compactum. He remarks that it is not 

 impossible, that the plant may be identic with the latter 1 ), but has 

 on the other hand seen every transition to L. circumscriptum, 

 and, therefore, he thinks it referrible to this. However, if it may 

 be considered a specific character whether the conceptacles of 

 sporangia grow down into the frond, or not, L. circumscriptum 

 must only with regard to this character be regarded a spedes 

 different from the older L. compactum. In the former the concep- 

 tacles never grow down into the frond according to Stromfelt. 2 ) 

 I have, too, collected rather numerous specimens of this species 

 fully coinciding with Stromfelfs description, and the immersed 

 conceptades do not become overgrown. On the other hand, in 

 L. circumscriptum /? validum, as Rosen vinge remarks 1. c. „af- 

 kastes kun Laaget, men ikke hele Konceptakiets Loft, og idet dette 

 og de mellem Konceptaklerne liggende Partier fortsætte Væxten, 

 bliver Konceptaklerne overvoxede". The conceptacles of sporangia 



*) „Det er ikke umuligt, at denne form kan være identisk med L. compactum. 



Kjellm." 

 2> i Algveg. Isl. p. 20. 



