38 M. FOSLIE. [1905 



botrytoides of the same species. They are often only distinguish- 

 able by the parting of sporangia. 



The conceptacles of sporangia are usually spread over the 

 whole of the frond, seldom crowded as in several other species. 

 They are convex, but little prominent, sometimes indistinctly marked, 

 250 (200)— 400 p- in diameter, and are gradually overgrown. The 

 roof is intersected with 30—60 muciferous canals. The sporangia 

 are four-parted, 100— 150 // long and 30 — 50 /j- broad. The cysto- 

 carpic conceptacles are conical, sometimes low, and of about the 

 same diameter as those of sporangia. 



The species — as far as is hitherto known — occurs sporadi- 

 cally, often together with other species in a depth of 3 — 15 fathoms. 

 However, I only met with a small number of specimens. It 

 occurs both on the open coast and in places fairly sheltered, and 

 is fructiferous in the months of June — September. 



Area: Norway : From the north-eastern boundary to Tromso (!) 

 (Karlso, Kj ell man); Iceland, the Eskifjordur (Strom felt). 1 ) 



9. Lithothamnion fornicatum Fosl. 



Contrib. It (1891), p. 3, pi. 1—2, Nonv. Lithoth. (1895), p. 36, Rev. Syst. 

 Surv. Melob. (1900), p. 12; De Toni, Syll. Alg. IV (1905), p. 1734; Lithothamnion 

 dehiscens Fosl. Norw. Lithoth. (1895), p. 45. 



f. subsphcerica Fosl. mscr. 



Lithothamnion fornicatum f. sphserica Fosl. Rev. Syst. Surv. Melob. (1900), 

 p. 12 (Norw. Lithoth. pi, 12, fig. 1). 



Frond spherical or depressed-spherical, repeatedly subdichoto- 

 mously branching from the centre, branches erect, straight and 

 fastigiate. 



f. dimorpha Fosl. mscr. 



Lithothamnion dimorphum Fosl. Norw. Lithoth. (1895), p. 40, pi. 10; Rev. 

 Syst. Surv. Melob. (190C), p. 12; De Toni, Syll. Alg. IV (1905), p. 1735; Litho- 

 thamnion fruticulosum f. fastigiata Fosl. Norw. Lithoth. (1895), p. 18, t. 5. 



f. apiculata Fosl. mscr. 



Lithothamnion apiculatum Fosl. f. typica, f. parvicocca Fosl. Norw. Lithoth. 



*) I have not seen any specimen of L. intermedium in the sense above taken 

 from Iceland, nor did the species occur among numerous Lithothamnia 

 collected by Mr. J 6 n s s o n in several places on that coast. On the other 

 hand it seems probable that the alga should occur there. 



