114 



or those in the mentioned specimen of the latter from Mandal, but 

 a little larger, convex or nearly hemispherical, with a single orifice, 

 about 250—300 p. in diameter. They are apparently not yet fully 

 developed, nor did I succeed in finding the spores. 



Relation to other species. As remarked, the present species 

 is closely related to L. polymorphum with regard to the colour 

 and the shape of the conceptacles of sporangia, and it, perhaps, 

 is nothing more than an epiphytic form of this species, analogous 

 to the same form of L. flavescens. However, it on the other side 

 differs especially by its surface being smoother than in any form 

 of L. polymorphum, not provided with excrescences, frequently 

 larger conceptacles, the roof of which is intersected with smaller 

 and more numerous muciferous canals, and so also with reference 

 to the structure. I, therefore, at least for the present consider it 

 an independent species. Sterile and somewhat faded specimens 

 appear more easily to be confounded with L. flavescens than with 

 any other known species. 



Habitat. It has hitherto been met with only on a single 

 specimen of another Lithothamnion, which seems to belong to L. 

 fruticulosum f. flexuosa, or perhaps is a form of L. tophiforme,. 

 taken on a depth of 5 — 6 fathom, on hard bottom in an exposed 

 locality. It bears mature sporangia in the middle of June. The 

 formation of carpospores appears to set in later. 



Occurrence. Only found at Lyngo in the neighbourhood of 

 Tromso, rare. 



Sectio II. Evanidae P'osl. mscr. 

 Conceptaculis sporangiferis superficialibus vel immersis, nunquam -nnatis. 



Lithothamnion congregatum Fosl. mscr. 



L. fronde libera in fundo jacente, subglobosa, demum fornicata,. 

 diametro usque ad 15 cm., roseo-purpurea, irregulariter subdicho- 

 tome ramosa; ramis brevissimis, confertis, inferne plus minusve 

 coalitis, teretibus, subcylindricis, circa 1 mm. crassis, fastigiatis,. 

 apicibus obtusis. Tab. 20. 



