No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 81 



Area: Norway: Haugesund(I) 1 ); FYedriksvaern (!), Drobak 

 (Gran!,!) and Nesodden in the Christiania Fjord (Schreiner !); 

 Sweden? 2 ) Denmark (Rosenvinge!); Helgoland (Kuckuck!); 

 the Faeroes (Jonsson, Borgesen!); Scotland: Berwick (Bat- 

 ters!); Ireland: West coast (Johnson)? Lame, Co. Antrim 

 (Hanna!); Atlantic coast of North America: Newport, R. I. (Col- 

 lins!), Kennebunkport, Me. (Collins!), Halifax Harbour, N. S. 

 (Mack ay, Howe!) 3 ) Newfoundland (Waghorne!). 3 ) 



3. Phymatolithon investiens Fosl. mscr. 



Lithothamnion investiens Fosl. Norw. Lithoth. (1895), p. 129, t. 22, fig. 2—5: 

 Rosenv. Deux. Mem. Alg. Mar. Gronl. (1898), p. 11? Jonss. Mar. Alg. East-Greenl. 

 (1904), p. 6? De Toni, Syll. Alg. IV (1905), p. 1731. 



f. torosa Fosl. . 



Rev. Syst. Surv. Melob. (1900), p. 11; Lithothamnion glaciale f. torosa Fosl. 

 Norw. Lithoth. (1895), p. 13, t. 1. 



f. ocellata Fosl. mscr. 



Lithothamnion ocellatum Fosl. Norw. Lithoth. (1895), p. 1 12. t. 19, fig. 10. 

 Phymatolithon ocellatum Fosl. List of Lithoth. (1898), p. 8; Rev. Syst. Surv. 

 Melob. (1900), p. 9; De Toni, Syll. Alg. IV (1905), p. 1725. 



Syn: Lithoph} r llum zonatum Fosl. Contrib. I (1890), p. 10. 



This species covers or encompasses other calcareous algse, 

 particularly Lithothamnion TJngeri, L. soriferum, L. tophiforme, 

 and L. glaciale, possibly also other hard objects. In specimens 

 of L. soriferum or L. tophiforme lying freely on the bottom with 

 the central branches rather- crowded, but the outer ones divaricate, 

 the former part of the alga is collectively loosely encompassed by 

 Ph. investiens, but the outer branches individually. The encom- 

 passing crust of the latter species is 0,5 — 2 or up to 3 mm. thick. 



!) I assume that some specimens bearing conceptacles in which sporangia have 

 not been found belong to this species. They were picked up at Salhus 

 near Haugesund from a depth of 8 — 10 fathoms in company with Litho- 

 thamnion Iceve and L. Sonderi. 



2 ) From Gullmarfjord I have seen a very small and sterile crust together with 

 Lithoth. Sonderi which probably belongs to this species. 



3 ) The specimens from Halifax and Newfoundland bear conceptacles, but I 

 have not found sporangia. Therefore, it is uncertain whether they belong 

 to Ph. IcBvigatum or perhaps to Ph. polymorphum, probably however to 

 the former species. 



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