100 



but especially between the knobs or short branches of younger 

 specimens so as to cover the animals. This is, however, seldom, 

 and in typically developed specimens not too much attacked I al- 

 ways found only the primary crust. If the crust by and by fully 

 encompasses the object, or this is not of very small size, the plant 

 appears to loosen itself in a later stage of development, sometimes 

 even, not till the branches are much developed, or the plant appa- 

 rently is nearly full-grown. On the other hand it at length always 

 loosens itself from the substratum; at first a part of the crust 

 disappears or loosens and by and by the whole crust of parts of 

 it together with some branch-system, so that more loosened indi- 

 viduals arise from one fastened. These continue their growth and 

 form at length irregular or subspherical masses, whose longest 

 diameter gets up to about 7 cm. Pl. 17, fig. 6 — 7. The branches 

 especially of loosened individuals often bear wart-like processes or 

 short branchlets, which in the upper part occasionally may be 

 rather crowded. 



I do not know whether the plant also develops freely on the 

 bottom. However, I have seen some younger specimens apparently 

 freely developed and probably belonging to the same form. 



An American specimen kindly sent me by Mr. Collins in 

 habit stands between the specimens figured pl. 17, fig. 1 — 2, and 

 it most probably belongs to f. Granii, but it is sterile and, there- 

 fore, the determination not quite certain. The crust is very thin, 

 partly disappeared and the plant nearly loosened from the object, 

 a small stone, which it apparently has nearly encompassed. Col- 

 lins' collection B. „Eagle Island, Maine. In pools at dead low- 

 water." The specimen on the other hand somewhat reminds one 

 of certain forms of L. fruticulosum. Cp. Hauck, Meeresalg. t. 

 5, fig. 4. However, in overgrown conceptacles I only found bi- 

 sporic sporangia, but they were smaller than in the named form. 



As remarked above I consider f. Rosenvingn to be the most 

 extreme form of the species, characterized by its fan-shaped rami- 

 fication and more or less compressed branches, analogous to L. 

 tophiforme f. alcicomis, but on the other hand showing the most 

 close affinity to f. Granii. A Greenlandic specimen kindly com- 



