No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 67 



The species is nearly related to L. nodulosum, particularly f. 

 gracilescens and f. saxatilis. It occurs in places sheltered, in fjords 

 or sounds, in a depth of 3 — 12 fathoms. It often forms small 

 banks, but it is nearly always sterile or sparely fructiferous, at 

 least along the coast of Norway. Specimens provided with repro- 

 ductive organs have been taken in the months of March — August 

 and December. 



As to the geographical distribution, the specimens I have seen 

 from Denmark partly resemble typical f. pusilla, partly approach 

 stunted forms of L. nodulosum f. gracilescens. Cp. under the 

 latter species. It does not seem to occur in any great number 

 on that coast, being known from six places, whereas it is abun- 

 dant in several places along the coast of Norway, in most cases 

 forming small banks. The form occurring on the coast of Scotland 

 partly resembles typical f. pusilla, but is mostly only 1 — 2 cm. in 

 diameter, partly approaches a stunted and delicate L. nodulosum 

 f. gracilescens, '{. e. it is provided with lateral wartlike processes 

 or short branches, like the above mentioned ones from Denmark, 

 and showing a tendency to form small bundles. 



Area: Norway: Lodingen and Korsnes in Nordland, f. pu- 

 silla Q), the Trondhjem Fjord, f. pusilla^), Moldoen, f. pusilla, f. 

 similis (Ostergren!), Espevasr, f. pusilla (Gran!), Haugesund, 

 f. pusilla (W i 1 1 r o c k, A r e s c h o u g, N o r u m !), Mandal, f. unci- 

 nata, f. pusilla (Wille!,!), Kragero, f. uncinatal, the Christiania 

 Fjord, f. pusilla (Schreiner!), Denmark, f. pusilla (Rosenvinge!); 

 Scotland: Port Bannatyne of Bute, Cumbrae, Arran, f. pusilla, f. 

 similis (Holmes, Batters, Robertson!) 1 ); Atlantic coast of 

 North America: Penobscot Bay, Me., f. pusilla? (Collins!) 2 ) 



20. Lithothamnion calcareum (Pall.) Aresch. 



In J. Ag. Spec. Alg. 2 (1852), p. 523; Millepora calcarea Pall. Elench. (1766), 

 p. 265, partim (non Ell. et Sol. ?). 



!) The species perhaps also occurs on the coast of the Orkneys. Cp. under 

 L. calcareum. 



2 ) A few specimens examined from that place seem to be referable to this 

 species. They have been picked up from a depth of 10 fathoms and re- 

 semble a small f. pusilla in habit and in structure, but, unfortunately, they 

 are sterile. 



