146 



Rélation to otJwr spedes. As remarked under L. congregatum 

 these species are often very difficult to distinguish in a not full- 

 grown stage, and even older specimens of the present species may 

 be confounded with not full-grown ones of the former. On the 

 other hand it in some respects shows råtner close affinity to other 

 species, as L. gracilescens, L. apiculatum and even L. fruticulo- 

 sum, and sterile specimens are easily confounded with the one or 

 other, though rather seldom with L. fruticulosum. It requires 

 closer examination of a number of fertile specimens, and it pro- 

 bably includes more forms, but must on the other hand be con- 

 sidered an independent species. 



Habitat. The plant lives on a depth of 3 — 10 fathom, and 

 it prefers rather hard bottom; though also occurring on looser and 

 somewhat clayish bottom, partly in protected partly in somewhat 

 exposed localities, but not on the open coast. It sometimes forms 

 isolated banks sometimes grows in company with other species. 

 The species is very scantily provided with organs of propagation 

 in the. later half of July. 



Occurrence. Found in Sorfjorden in Skjorn, rather local but 

 abundant, partly together with L. congregatum; Brækstad (Orlandet), 

 local but abundant; at Bejan, local and rather scarce together with 

 other species; and at Frojen together with L. tophiforme, rare. 



Lithothamnion byssoides (Lam.) Phil. 



in Wiegm. Arch. p. 388; Millepora byssoides Lam. Hist. Anim. 2, p. 312. 

 Descr. et Fig. Lithothamnion b}rssoides Hauck, Meeresalg. p. 275, t. II, fig. 1.. 

 Fig. Spongites „ Kiitz. Tab. Phyc. 19, t. 99. 



Syn. Lithoth. byssoides Aresch. in J. Ag. Spee. Alg. 2, p. 522; excl. syn. plur.. 



Remark on the determination of the species. With some- 

 doubt I re ter a couple of fragmentary specimens to this species, 

 agreeing well with the description and the cited figures, only larger,. 

 or of subspherical specimens that have been about 10 cm. in dia- 

 meter. They are, however, sterile, and I have not seen any au- 

 thentic specimen of L. byssoides, nor do I know whether the con- 

 ceptacles of sporangia become overgrown in the latter. I havet 

 not found such in the named fragments. 



