XVI FOSSIL ARCHEGONIATES S83 



been described under the name Danwopsis. The other living 

 genera are not known as fossils, although certain fossil genera 

 seem to be related to them. Thus Asterotheca and Scolecop- 

 teris have been placed in the Angiopteridese, Ptychocarpus in 

 the Kaulfussiese. 



Besides the forms w^hich are unquestionably to be referred 

 to the Marattiales, there are a good many types of Palaeozoic 

 Ferns which show apparent resemblances to the true Maratti- 

 acese in the structure of the sporangium, but which have the 

 individual sporangium entirely distinct, instead of more or less 

 united with its neighbours as in the typical synangium of most 

 Marattiacese. This free sporangium is structurally like that 

 of such forms as Angiopteris, in which the sporangia are nearly 

 separate, and not improbably represents a Marattiaceous type 

 in which this tendency is carried further than in any of the liv- 

 ing genera. In still other forms of supposed Marattiaceous 

 afifinity, e. g., Urnatopteris (Potonie (3), Fig. 68), the spo- 

 rangia are borne upoti sporophylls, which are completely cov- 

 ered with them, as in the fertile fronds of Osmunda or Bo- 

 trychium. In all of the living Marattiacese except Dancea, the 

 synangia are borne upon unmodified leaves. In Dancea, how- 

 ever, the segments of the sporophyll are much contracted, and 

 the large synangia almost completely cover the lower surface 

 of the pinnae, and in this respect it suggests an approach to 

 those Palaeozoic types in which the lamina of the fertile leaves 

 is entirely wanting. 



It is not unlikely that some of the Carboniferous Maratti- 

 ales were more or less synthetic types, connecting the typical 

 Marattiaceae with the later developed Leptosporangiates. The 

 genus Senftenhergia (Potonie (3), Fig. 86), for example, 

 seems to resemble to a certain extent both Marattiaceae and 

 Schizseaceae, while Renaultia (Sturiella) has been compared 

 with both the Osmundaceas and Schizaeaceae. 



The Marattiaceae seem to have maintained their ascendency 

 well into the Mesozoic. Raciborski (see Scott (i), p. 303) 

 found in upper Triassic beds about 70 per cent, of the Ferns to 

 be Marattiaceae ; but in lower Jurassic beds there was a remark- 

 able falling off in their number, only about 4 per cent, being 

 referable to the Marattiaceae. At the present time their num- 

 ber is less than one per cent, of the living species of Ferns. 



While there is some evidence of the presence of leptospo- 



