M. FOSLIE. 



[1900 



Gen. Arehæolithothamnion (Rothpi.) Fosi. 



Sporangia cylindric-bean-shaped to roundish ovate (unparted 

 or cruciate?), grouped in zonate or conceptacle-like, subimmersed 

 or superficial, more or less regular sori, each through an elongated 

 tip corresponding with muciferous canals in the cover and isolated 

 by enduring or sometimes at length destructible walls. 



Carpospores in superficial, conical conceptacles with a coarse 

 apical pore, arising from every part of the almost plain „conjuga- 

 tion cell". 



Sect. I. Endosporæ Fosl. 



The sporangia beds at length growing down into the frond. 

 A. cenomanicum (Rothpi.) Fosl. 

 A. turonicum (Rothpi.) Fosl. 

 A. gosaviense (Rothpi.) Fosi. 

 A. nummuliticum (Gumb.) Fosl. 1 ) 

 A. Aschersoni (Schw.) Fosl. 



A. erythraeum (Rothpi.) Fosl. (= A. Aschersoni f.? Sporo- 

 lithon ptychoides Heydr.) 



f. dura (Heydr.) Fosl. 



f. mollis (Heydr.) Fosl. 

 A. Rothpletzi (Trab.) Fosl. 



A. mediterraneum (Heydr.) Fosl. (= A. Rothpletzi?) 

 A. Giimbeli Fosl. mscr. (L. torulosum Rothpi. ex parte). 2 ) 



7. 



9. 

 10. 



A.? Rosenbergi (K. Mart.) Fosl. 



1 ) L. nummuliticum Gumb. appears also to include a true Lithotliamnion 

 (L. torulosum?). Cp. Gumbel, Nullip. t. 1, fig. 2 e, which most probably 

 represents conceptacles of sporangia of the latter genus. 



2 ) It seems to be beyond doubt that the section of the type specimen of 

 ■ , Litliothamnion torulosum Gumb. pictured by Rothpletz, Foss. Kalkalg. 



jft* 



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