124 M. FOSLIE. [1905 



sporangia are unknown, it most probably represents a stunted f. 

 intermedia. 



In Ktit zing's herbarium is not to be found any specimen 

 under the name of Phyllactidium cohfervicola (Phyc. gener. p. 295). 

 There is however a specimen bearing the following label: „2Ielobesia 

 farinosa & Hapalidium Phyllactidium. Ad (Chondriam) Laurenciam 

 condensatam. Neapel." (Cp. Spec. Alg. p. 695). The calcareous 

 algse belong to 21. farinosa and L. pustulatum-. This specimen 

 is not the one which is figured in Tab. Phyc. XIX, t. 92 under 

 the name of Hapalidium Phyllactidium, but the latter probably 

 also belongs to L. pustulatum. 



According to the liberal communication of Madame A. Weber- 

 van Bosse the genus Pneophyllum does not occur in Ktit zing's 

 herbarium. It is, however, stated 1. c. that Pneophyllum fragile 

 covers Ryncliococcus coronopifolius. Under this species two spe- 

 cimens with attached calcareous algae are found in the herbarium. 

 One of them was kindly sent to me for examination. The upper 

 part of this specimen is covered with a well developed Melobesia 

 farinosa. Associated with the latter a few and very small frag- 

 ments of Lithophyllum pustulatum occur between the branches 

 of the host plant and in the top of a branch. The description 1. 

 c. seems partly to correspond to 21. farinosa, but chiefly and most 

 nearly to L. pustulatum. I, therefore, think myself entitled to 

 presume that Pneophyllum fragile belongs to the latter species. 



The great variation of L. pustulatum is mainly due to the 

 fact that it occurs on very heterogeneous substrata, particularly 

 on a number of different other -algse. When the substratum is of 

 a fairly firm consistency, the crust always becomes thicker than 

 if the consistency of the substratum is loose. In the latter case 

 the alga in question, as a rule, also becomes of small extent. This 

 concerns all forms, but the f. macrocarpa and f. Laminarice are, 

 for the most part, larger and more vigorously developed than the 

 others. -The crust also becomes more or less irregular, when the 

 substratum is uneven. On filiform algae most forms embrace the 

 host plant cylindrically. Sometimes the alga grows in part freely. 

 This I have seen particularly in specimens growing on Yalonia 



