No. 5] REVISED SYSTEM. SURVEY OF THE MELOBESIEAE. 9 



Sect. II. Episporæ Fosl. 



The sporangia beds not growing down into the frond. 



11. A. mirabile Fosl. 



12. A. Fosliei (Heydr.) Fosl. 



13. A. crispatum (Hauck) Fosl. ex parte? Cfr. Fosl. Syst. Surv. 



Gen. Phymatolithon Fosl. 



1898. Syst. Surv. 



Conceptacles of sporangia soriform, immersed, at length cup- 

 shaped; sporangia 1 ) betvveen more or less destrubtible walls, through 

 gelinated, at length loosening tips corresponding with muciferous 

 canals in the roof. 



Conceptacles of cystocarps slightly convex, at length cup- 

 shaped, immersed, with a central pore ; carpospores arising hetween 

 paranemata. 



1. Ph. polymorphum (L.) Fosl. 



f. tuberculata Fosl. 

 f. valida Fosl. 

 f. papillata Fosl. 



2. Ph. ocellatum Fosl. 



3. Ph. lævigatum Fosl. 



Gen. Clathromorphum Fosl. 



1898. Syst. Surv. 



Conceptacles of sporangia soriform, immersed, the central part 

 of the roof at first slightly convex or forming light dots on the 



t. XVII, fig. 6 represents a true Lithoihamnion with an overgrown con- 

 ceptacle of sporangia and not any sexual organ of Archæolithothamnion 

 or Lithoihamnion. Cp. Rothpl. 1. c. p. 318. The last named organs 

 are superficial in both the said genera and do not (or very seldom?) grow 

 down into the frond. Besides, in the latter case the shape of the concep- 

 tacle should be another. Nor does the said conceptacle resemble any of the 

 reproductive organs in Goniolithon or LithophyUum, while on the cther 

 hand it fully agrees with overgrown conceptacles of sporangia in Litho- 

 ihamnion. Consequently fig. 2 1. c. represents another species, an Archæo- 

 lithothamnion, for which I propose the above narae. 

 1 ) The sporangia in this and the following genera are of a more or less 

 oblong shape, convex-concave and zonate t\vo-or four-parted. 



* - Vs 



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