20 ARKIV FÖR BOTANIK. BAND 17. N:0 1. 



iiuut of the ►Swedish .State Museum of Natural History there 

 arc a few fertile .specimens of Hausmannia which seem to 

 throw some light on this question. 



Hausinaiiiiia Forcliliainnieri Barth, ssp. deiitata Moll. 



(PI. 2, figs. 19-24.) 



The best of the specimens examined has previously been 

 figured by Möller (11)02, pi. 4, fig. 15) as the type of his ssj). 

 dentata of Hausmannia Forchhammeri Barth. It consists of 

 the impression of the lower surface of a part of the frond 

 with many of the sporangia and remains of the tissue of the 

 leaf adhering to the surface of the rock. Where the sporangia 

 are absent their shape can still to some extent be studied by 

 means of the impressions they have left on the surface of the 

 rock. Where the sporangia are present, their shape and struc- 

 ture are entirely hidden by the superimposed carbonized re- 

 mains of the foliar tissue. In order to study the sporangia 

 it is necessary to remove pieces of the carbonaceous film con- 

 sisting of the leaf tissue and the si)orangia and turn them 

 over so that the sporangia can be observed from below. 



The sporangia cover the whole of the lower surface of 

 the frond, and it is difficult to distinguish the sori. The spor- 

 angia in each sorus seem to be more numerous than in Dictyo- 

 pliyllum, but it is impossible to count them (pi. 2, fig. 19). 

 A peculiar feature is the occurrence of hair-like structures 

 preserved as faintly yellowish impressions on the surface 

 where the covering film of foliar tissue and sporangia has 

 been removed (pi. 2, fig, 20, which shows a sorus from which 

 the sporangia have been removed). These structures some- 

 what suggest the filamentous paraphyses accompanying the 

 sporangia in Dipteris. 



The sporangia seem to have been roundedly obovoid. 

 Usually their outline ajjpears almost circular, but in no case 

 could their whole circumference be traced; it is probably al- 

 ways the elongated basal part that has been broken, causing 

 the sporangia to look more rounded than the}^ were. The dia- 

 meter of the rounded part of the sporangia is 0,i8 — 0,24 mm. 



The annulus is distinct, but, on account of the broken 

 condition of the sporangia, it can in no case be traced round 

 the whole sporangium. It is not possible, therefore, to decide 



