133 



or narrower part of the peripherical portion is always sterile, and 

 the first developed conceptacles in the centre frequently are emp- 

 tied before the others are developed. Bearing sporangia for the 

 second time or more, this development is less regular, or the 

 named organs are developed from the centre of smaller and new- 

 formed crusts upon the older. 



The conceptacles are shown from the surface of the frond at 

 first as faintly light circular and not depressed points about 200 

 — 300 /* in diameter. Later the central portion of these points 

 gets decorticated, by and by forming a globular and very shallow 

 deepening about 100 — 150 p- in diameter, a part of the roof of 

 the conceptacles, and this part is intersected with about 20 — 30 

 rather coarse muciferous canals, or the roof is not to be distin- 

 guished- from the other parts of the surface of the frond before 

 the named central portion gets decorticated. At maturity this 

 central portion at first gets dissolved, and at the same time the 

 surrounding parts of the roof become lighter and by and by dis- 

 appear, leaving, owing to the densely crowded conceptacles, fre- 

 quently six-angular holes, the emptied conceptacles, looking as a 

 mesh-work, with thin walls. By and by a smaller or greater 

 part of the dissepiments also gets dissolved. The scars are effa- 

 ced by a new thickening layer of the frond, and when replenished 

 it often looks, as if the surface was areolate, but the effacing 

 also takes place by new local formations of tissue stretched over 

 more scars, and then the surface becomes rather irregular. 1 ) The 

 bisporic sporangia are rather varying, 200 — 300 \i long and 70 — 

 TOO fi broad. 



Relation to other species. It in some respects shows greater 

 affinity to L. compactum and may in a sterile state occasionally 

 be confounded with that. However, it differs both in regard to 

 the conceptacles of sporangia as well as the structure and other 

 characters. Cp. under the latter. It is more easily confounded 

 with a couple of the below described species. 



Habitat. The plant lives both in the litoral and sublitoral 



*) Rosenvinge mentions 1. c. such areolating to be recognized by densely 

 crowded conceptacles also before they are opened. 



10 " 



