215 



Lithothamnion Philippi. 



Subgenus Eulithothamnion Fosl., char. inut. 

 Concoptacles of sporangia superficial or more or less immersed; 

 the roof plane or vaulted. 



1. Lithothamnion laeve (Stromf.) Fosl. 



FosLiE in K. Rosenv. Deux. Mem., 1898, p. 14; Rev. Surv., 1898, p. 15; Remarks, 190G, p. Ki and 131; 



Algol. Notiser V, 1908, p. 6; K. Rosenvinge, Mar. Alg. N. K. Greenl., 1910, p. 100, fig. 1; Lemoine, 



Struct., 1911, p. 74, figs. 36 and 37. 

 Lithophijlliim Uevr Stromfelt, Isl., 1886, p. 21, tab. I fig. 11-12. 



Lithothamnion Lenormandi (Aresch.) RosanofT, f. Iceve (Stromf.) Foslie, Contrib. II , 1891, p. 11. 

 Lithothamnion tenuc K. Rosenvinge, Grenl. Havalg., 1893, p. 778, figs. 4—7 (Alg. mar. Gr. p. 58). 

 Litliolliamnion Strdmfeltii Foslie, Norw. Forms, 1895, p. 145. 



This species, very common in the Arctic Sea, has been found in two localities 

 in the sea north of Sealand, the most southerly stations known in Europe. The 

 specimens from the Kattegat were mentioned by Foslie in 1906 (Remarks p. 131). 

 I have examined the structure of the specimen from the Sound which was preser- 

 ved in Juel's liquid. The species is easily distinguished from L. Lenormandi by 

 its smooth surface and the large conceptacles. 



The thallus in the Danish specimens is thin. The filaments of the hypothallium 

 are, as pointed out by Mme Lemoine, loosely connected. When seen from the surface, 

 they show here and there transversal fusions. The cells are 21 — 33/y. long, 7,5 —9,5 fi broad. 

 According to Mme Lemoine, the undermost cells of the hypothallium form rectangular 

 cells directed towards the sub- 

 stratum, thus constituting "une 

 rangee de rhizoides obliques". 

 I have not been able to see 

 anything of this kind in the 

 specimen examined. The fil- 

 aments of the perithallium are 

 composed of a small number 

 of roundish cells, 7 // thick or 

 a little more, up to 10 a. These 

 dimensions, which I found in 

 specimens from both localities, 

 are in accordance with Foslie's 

 statement (Remarks p. 18), 

 while Mme Lemoine gives the 

 thickness as only 4 — 5 fx K The 



> This indication is not in accor- 

 dance with the figures of Mme Lemoine, 

 in which the cells are thicker. 



