106 



mentioned by Kjellman 1. c. appear to have been younger and 

 those mentioned by Rosen vinge fully developed or emptied. 

 Greenlandic specimens accord in this respect with specimens that 

 I got from Spitzbergen (pi. 19, fig. 3), American (pi. 19, fig. 4) 

 and Norwegian (pi. 19, fig. 1 — 2), in which I also found younger 

 conceptacles agreeing with younger ones in an authentic specimen 

 from Kjellman's collection, gathered at Novaya Zemlya. The 

 named organs are different in both species, although they, in cer- 

 tain states of development, may be rather easily confounded. The 

 above mentioned falling away of the whole roof in L. compaction 

 does not take place successively and in the same manner as in 

 L. circumscriptum, and even in this case the conceptacles may be 

 overgrown. If, however, the holes become filled with new local 

 formations of tissue, as apparently often being the case, such filled 

 conceptacles frequently are to be seen on a section, which, so far 

 as my experience goes, never is the case in L. circumscrip)tum, 

 showing that the thickening meristema in L. compactum is super- 

 ficial, overlapping this new formations, but in L. circumscriptum 

 lying be^ow the basal surface of the conceptacles. . I have even 

 seen the greater part of a new crust upon an older being rubbed 

 or dissolved together with the conceptacles. PI. 19, fig. 2. I, 

 therefore, suppose it to be specimens in which the whole roof of 

 the conceptacles is fallen away, that Rosen vinge regards as 

 transitions to L. circumscriptum, and such specimens occasionally 

 rather remind one of the latter. However, the last named species 

 never attains the thickness of L. compactum, scarcely up to 1 mm., 

 and the peripherical portions always are thinner than the internal, 

 while in L. compactum the former sometimes ma}' be even thicker 

 than the latter and the plant slightly concave. Besides, the con- 

 ceptacles in L. circumscriptum occupy a sharply defined zone, 

 developed successively from the centre towards the periphery, so 

 that the inner frequently are emptied before the outer are founded, 

 but always with a sterile peripherical portion. In L. compactum, 

 on the other hand, they are contemporary developed over the 

 whole frond and frequently even close to the margin. 



Relation to other species. As remarked by Prof. Kjellman 



