227 



Meer., 1904, p. 'A2 TnC II figs. 15—23; Lemoine, Reparl. du Mai'il pi. I fig. 14. - It is 

 "flabellate, the Ijranch-syslems spreading like a fan in all directions from the centre 

 of the frond ahnosl in one phine. Sometimes it forms rather thiclv and compressed 

 fronds" (Foslie, Remarks p. 69). 



3. F. palmatifida Foslie, Some new or cril. Lilh., 1898 p. 6, Remarks p. 69; 

 Lemoine, Repart. du Maerl pi. I fig. 3, Structure, p. 104. — "With branches more 

 distant and palmate" (Foslie, 1905). 



4. F. siibsimplex (Batt.) Foslie, Norw. Litholh. 1895 p. 62 pi. 16 figs. 38—42; Le- 

 moine, Rep. du Maerl pi. I fig. 10, Structure p. 104. Frond "simple or feebly branching" 

 (Foslie Remarks). 



There are no distinct limits between these forms, which occur together at 

 the same locality. 



The structure has been mentioned by Mme Lkmoine (Structure p. 105), whose 

 description may here be referred to. It will suffice to add some small remarks. 

 According to Mme Lemoine there is always at the periphery a 

 cortex composed by 5 or 6 layers of cells which are rectangu- 

 lar, while the other cells are ovoid. I have certainly observed 

 such a cortex in some cases, but it does not occur normally; 

 the outer tissue, in the sections examined by me, more fre- 

 quently consisted of cells of the same shape as those of the 

 inner tissues (fig. 144). Transverse fusions between the cells are 

 very frequent. The size of the cells is somewhat variable, generally 

 they are 9 — 13// long, 5 — 7 « broad. Starch grains were found in 

 great quantity in all cells except the outermost. On being treated 

 with acetic acid and iodine in potassium iodide the starch grains 



swelled and filled the cells with a homogenous violet-brown mass. 



Fig. 144. 



Lithulltamnion calcarciini. 

 Transxcrse section of 

 Ironrl. at the iicripheiv- 

 Several transverse fusions. 

 350 : 1 . 



they were almost 



In a specimen from Trindelen (ZB, July) empty concep- 

 tacles were found, the kind of which could not be determined 

 entirely immersed. Possibly they were antheridial conceptacles. 



The species has been found in 17 to 30 meters depth, on gravelly or stony 

 bottom, generally associated with other Lithothamnia, in particular Lith. glaciale, 

 and with Corallina officinalis. 



Localities. Kn: ZB, near Trindelen, 28—30 meters. - Ke: IL and IP, Fladen ; IK, Lille Mid- 

 delgrund. — Km: La?s0 Hende, clayey bottom, small fragments (C. H. Ostenfeld). 



Subgenus Phymatolithon Foslie. 



In 1898 Foslie (Sysl. Surv., p. 4) established the genus Phyinatolithon, founded 

 on Lithothamnion polymorphiim, and distinguished from the genus Lithothamnion 

 chiefly by immersed conceptacles and the roof of the sporangia! ones being de- 

 pressed or cup-shaped. Later on he has referred L. Icevigatum and another species 

 to the same genus. I must, however, agree with Mme Lemoine, who observes (Struct. 



29* 



