125 



culatum Kjellm. Spetsb. Thall. 1, p. 3) from Spitzbergen that 

 he has seen from Kjellman's collection also the last named spe- 

 cies is probably included in his L. fasciculatum, but not only this, 

 as quoted above under L. glaciate p. 13 (41). 



With regard to L. soriferum Rosen v. I refer to what is 

 remarked under L. flabellatum. 



Relation to other species. The present species appears to be 

 more sharply defined than several other Lithothamnia. As the 

 conceptacles never grow down into the frond and the thickening 

 meristema apparently lies below the basal surface of the concep- 

 tacles, it really is most nearly allied to L. nodulosum, so far as 

 the latter hitherto is known, but it cannot be confounded with any 

 form of that species. However, on the other hand it in a sterile 

 stage may be confounded with more species of the section Innatce,. 

 in which overgrown conceptacles are not always to be found. 

 Thus as mentioned under L. fruticulosum f. flexuosa the typical 

 form sometimes is very difficult to separate from that, and f. glo- 

 bosa occasionally rather approaches L. dimorphum in habit. Besides, 

 sterile and slender specimens are easily confounded with L. flabel- 

 latum f. Oranii, and even such ones with younger conceptacles 

 of sporangia, although these species are quite different in their 

 typical development. 



Habitat. This species in general lives on sandy and shingly 

 bottom, frequently forming banks, and it appears to prefer some- 

 what sheltered places, here often growing on a depth of only 4 — 8 

 fathom, but in more exposed localities descending farther down, 

 to a depth of 10 — 15 or even 20 fathom, and it on the whole 

 descends farther down than other Lithothamnia, perhaps with ex- 

 ception of L. glaciate and L. boreale. It nearly always develops 

 freely on the bottom. I never met with certain specimens fastened 

 to any other object, but according to Kj ell man 1. c. some spe- 

 cimens of f. alcicornis plainly show that they have been at first 

 attached to some harder object. However, at Kvalsund I found 

 a younger specimen fastened to L. glaciate which most probably 

 belongs to f. squarrosa. The plant bears sporangia in July, Au- 



