M. FOSLIE. 



[1908 



host plant, a transverse section of the host plant with the epiphyte 

 attached will often show only a pluristromatic thallus in the latter, 

 if the section does not hit a marginal part. Some species thus 

 developed with single-layered hypothallium I have formerly referred 

 to CarpoUtJion subgenus of Litliopliyllum. By examining these 

 species more closely I have found a mostly small marginal portion 

 monostromatic with small and solitary cortical cells. This proves 

 that there is a near connection between the genera Melohesia and 

 Litliophyllum ; for — as far as I have hitherto seen — there is 

 no essential difference as to the reproductive organs. The species 

 mentioned below I, therefore, now refer to a new subgenus, Plio- 

 stroma, including M. zonalis which I used to refer to the sub- 

 genus Heteroderma. 



Melohesia (Pliostroma) zonalis (Crn.) Fosl. 



Rem. Melob. Herb. Crn. (1900) p. 3; Hapalidium zonale Crn. Not. Hapal. 

 (1859), p. 28 ^ pi. 21, fig. A, saltem pro parte ! Fl. Finist. (1867), p. H9; Hapa- 

 lidium coccineum Crn. Not. Hapal. p. 285 partim? Cfr. Fl. Finist. 1. c; Hapali- 

 dium phyllactidium Crn. Not. Hapal. p. 286, pi. 21, fig. B. ! Hapalidium confer- 

 voides Crn. Fl. Finist. p. 149 partim! Hapalidium roseum Crn. Fl. Finist. p. 149? 



f. typica. 



Melohesia zonalis Crn. 1. c; Fosl, 1. c. 



f. 7nyriocarpa (Crn.) Fosl. 



Alg. Not. V(1908), p. 201); Melohesia myriocarpa Crn. Fl. Finist. (1867), p. 150! 



I mentioned 1. c. that in an authentic specimen examined of 

 M. zonalis I had not seen solitary cortical cells. Still such ones 

 occur. In this monostromatic part of the thallus, the cells, when 

 seen from the surface, are partly subquadrate, partly and most 

 frequently elongated in the direction of the radius, 9—14 (18) [i 

 long by 7 (6)— 10 (12) jj.. Here and there occur hyaline cells 

 which resemble the same in M. Lejolisii. Cp. Rem. north. Lithoth. 

 p. 103. The cortical cells are small and most!}' oblong. They 

 bear a strong resemblance to the corresponding cells in M. Lejo- 

 lisii, but are partly a little larger and almost semicircular. The 

 central parts of the thallus attain to a thickness of up to 70 /i, 

 and are composed of up to ten layers of cells. In a transverse 



1) Owing to a lapsus calami it has here heen put down under lAUiophjilUun. 



