222 



var. colliciilosa (Fosl.) 



Lithothamnion coUiculosum Foslie, Contrib. II, 1891, p. 8, tab. 3 fig. 1 ex p.; Norw. Forms, 1895, p. 75 

 ex p.; Remarks, 1905, p. 34. 



Foslie has referred to L. coUiculosum specimens from two localities in the 

 western part of the Limfjord. They resemble arctic specimens of L. glaciale with 

 not much developed processes which are thicker than in L. glaciale f. Granii and, 

 as it seems, less closely placed, up to 4 mm high. The crust is well developed, 

 expanded, and contains conceptacles. These specimens were found growing on My- 

 tilus and stones. 



var. Granii (Fosl.) 



Lithothamnion flabellatiim K. Rosenv. f. Granii Foslie, Norw. Forms (1895) p. 70, tab. 17 fig. 1—7, 



tab. 22 fig. 1. 

 L. Granii Foslie, Remarks (1905) p. 59. 



All the other Danish specimens belong to this variety. It differs from the 

 typical L. glaciale by more closely placed, thinner and often more ramified branches. 

 The thickness of the branches, however, varies somewhat; it is lesser, for instance in f. 

 reducta Foslie. The crust is usually much developed and may be widely expanded 

 over the substratum. In the latter case the processes are frequently small, wartlike 

 and rather spread, and the crust then frequently contains numerous conceptacles 

 (fig. 138 A). When growing on pebbles on gravelly bottom it often completely en- 

 compasses the pebble, and when this is small, branches may project from it at all 

 sides. Usually however, they grow principally to one side, viz. upwards, and these 

 upward growing branches may branch repeatedly. In branching they often have 

 a tendency to take globular form, and such globular branch-systems may at last be 

 loosened, the conjunction with the pebble being given up. On gravelly bottom, loose 

 individuals, "iEgagropila-forms", exactly similar to these branch-systems, are often 

 found (Plate IV figs. 1 — 4). H. Jonsson assumes that the loose iEgagropila-forms of 

 L. Ungeri and L. tophiforme are produced in the same manner otT the shores of 

 Iceland ^ Probably loose individuals may also arise by division of other loose ones. 

 On gravelly bottom the plurality of the individuals may be loose (e. gr. Lille Middel- 

 grund, Ke). In the inmost localities in the Danish waters (Ks, Sa, Lb, 8b, !Sii) only 

 specimens with well developed crust but small processes were met with. 



The crust contains a hypothallium composed of few cell-layers from which 

 obliquely ascending filaments continuing in the perithallium are given off. The cells 

 of the hypothallium w^ere in the specimen examined 20 — 22 /j. long, 5 — 7 [j. broad. 

 Mme Lemoine states the dimensions for L. glaciale to be 12 — 18 x 2 p. The latter 

 figure, however, must be presumed to be exceptionally low. Mme Lemoine further 

 states that the hypothallium gives off a layer of rhizoids or rectangular cells in- 

 clining against the substratum ; this I have not found in the Danish specimens 



' H, Jonsson, Om Algevegetationen ved Islands Kyster. Botan. Tidsskrift 30. 1910 p. 322. — The 

 Marine Alg. Veg. of Iceland. The Botany of Iceland, Part I,i 1912 p. 154. 



