4 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 åa marginal part. Some species thus 
developed with single-layered hypothallium I have formerly referred 
to Carpolithom subgenus of Lithophyllum. By examining these 
species more closely I have found åa mostly small marginal portion 
monostromatic with small and solitary cortical cells. This proves 
that there is a near connection between the genera Melobesid and 
Lithophyllum; 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, Pl:o- 
stroma, including M. zonalis which I used to refer to the sub- 
genus Heieroderma. 
Melobesia (Pliostroma) zonalis (Crn.) Fosl. 
Rem. Melob. Herb. Crn. (1900) p. 3; Hapalidium zonale Crn. Not. Hapal. 
(1859), p. 284 pl. 21, fig. A, saltem pro parte! FI. Finist. (1867), p. 149; Hapa- 
lidium coceineum Crn. Not. Hapal. p. 285 partim?  Cfr. FI. Finist. 1. c.; Hapali- 
dium phyllactidium Crn. Not. Hapal. p. 286, pl. 21, fig. B.!  Hapalidium confer- 
voides Crn. FI. Finist. p. 149 partim! Hapalidium roseum Crn. Fl. Finist. p. 149? 
f. typica. 
Melobesia zonalis Crn. 1. c.; Fosl. 1. c. 
f. myrtocarpa (Crn.) Fosl. 
Alg. Not. V (1908), p. 201); Melobesia myriocarpa Crn. Fl. Finist. (1867), p. 150! 
I mentioned I. 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) p 
long by 7 (6)—10 (12) p. Here and there occur hyaline cells 
which resemble the same in M. Lejolisti. Cp. Rem. north. Lithoth. 
p. 103. The cortical cells are small and mostly oblong. They 
bear a strong resemblance to the corresponding cells in M. Lejo- 
listt, but are partly a little larger and almost semicircular. The 
central parts of the thallus attain to a thickness of up to 70 p, 
and are composed of up to ten layers of cells. In å transverse 
1) Qwing to a lapsus calami it has here been put down under Lithophyllum. 
