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is a well defined species. They are about 4 — 6 mm. thick. Upon 

 the primary crust new crusts are formed, sometimes closely united 

 to one another, sometimes and more often, in one and the same 

 specimen, rather loosely connected, with in part visible interwalls, 

 or covering extraneous objects. Together with the wart-like and 

 small prominences small lamels often are formed, with the edges 

 free and bent downwards, or gripe over and older prominence, 

 or at length form hollow prominences. These lamels are frequently 

 concentric zonated. The conceptacles grow down into the frond. 

 They are in a median section about 100 ft high and 200 — 250 in 

 diameter. I have not seen superficial conceptacles of sporangia, 

 nor do the sporangia appear to be known. I, however, found 

 some few other superficial conceptacles, which apparently are cy- 

 stocarpic ones, and probably those mentioned by Hauck 1. c. p. 

 272. They are hearly subhemispherical, with a single orifice and 

 about 300 — 400 fi in diameter. The third specimen rather differs 

 from the other two. It is of about the same thickness as these, 

 but the frond appears to be composed of minute lamels more or 

 less densely united. Seen from the surface these lamels are very 

 small and horizontally extended, seldom slightly raised, giving the 

 surface a rugged and squamellate appearance. It is sterile, and I 

 have not examined the structure, nor do I know whether it really 

 is a form of L. papillosum, or, more probably, belongs to another 

 species, not unlikely even of the subgenus Lithophyllum. It grows 

 together with a very small fragment of typical L. papillosum. 



Habitat. On the northern part of the coast the plant lives in 

 rockpools, or on nearly perpendicular rocks in the lower part of the 

 litoral region. It also occurs a little below extreme lo w- water 

 mark, to about 1 fathom, but I do not know whether it descends 

 farther down in the sublitoral region. On the south-western coast 

 I met with it in 2 — 3 fathoms water, as at Hvitingsø near Hauge- 

 sund, and in the Christiania-Fjord it has been tåken on a depth 

 of about 5 fathom. It appears in sheltered places as well as in 

 rather exposed localities, and it apparently develops organs of pro- 

 pagation nearly all the year at least in more southern waters. Thus 

 it is found near Tromso with ripe sporangia in the middle of June 



