292 



STUDIES IN FOSSIL BOTANY 



unassigned petrified sporangia, of Palaeozoic age, 

 as possess an annulus or other characters indicating 

 Filicinean affinity. In Figs. 1 1 1 and 112, examples of 

 Fern-sporangia from the English Coal-measures are 

 represented. In the former figure two sporangia are 

 shown, seated side by side on a fragment of leaf, in 

 which a vascular bundle with scalariform tracheides 



is present. It will be 

 noticed that the sporangia 

 are free from each other, 

 and that each shows a 

 cap-like annulus, or group 

 of enlarged cells, in the 

 upper part. The fructi- 

 fication is certainly not a 

 synangic one, but might 

 conceivably belong to 

 some Marattiaceous Fern 

 comparable to Angiopteris, 

 or might equally well 

 be compared either with 

 Schizaeaceae or Osmund- 

 An affinity with 

 the Botryopterideae is, 

 however, quite as probable (see next chapter). This 

 fructification may be distinguished as Pteridotheca 

 Butterworthii, after its discoverer. 



In Fig. 112, on the other hand, we have a section 

 passing through a large sorus, or rather a group of sori. 

 The plane of the section was no doubt approximately 

 parallel to that of the fertile frond, which was highly 

 compound and apparently of the Sphenopteris type, the 



Fig. hi. — Pteridotheca ButterwortJiii. Frag- 

 ment of a Fern - frond from the Coal- 

 measures, in vertical section, showing two 

 sporangia(j;«), each with an apical annulus, 

 and containing spores. In the tissue of the 

 leaf, part of a vascular bundle is shown, appap 

 x 34- Will. Coll. 1871. (G. T. G.) 



