XXl] POLYPODIACEAE 375 



(14 cm. in diameter), of which a portion is seen in fig. 277, was 

 described by Heer from Disco Island (Greenland) as a Carboni- 

 ferous species^ but afterwards correctly assigned to the Ceno- 

 manian series' This species is recorded also from the Lower 

 Cretaceous of Bohemia by Fric and Bayer^ Among examples 

 of petrified stems exhibiting a general agreement with Pro- 

 topteris punctata are those described by Stenzel^ from Turonian 

 rocks in Germany. In one of these, Rhizodendron oppoliense 

 Gopp., attention is drawn to branches given off from the stem 

 stele which have a solenostelic structure in contrast to the 

 dictyostele of the stem ; also to the minute structure of the 

 tracheae which appear to have their ends perforated, a feature 

 shown by Gwynne-Vaughan^ to be characteristic of the xylem 

 elements of many ferns. 



Protopteris Witteana Schenk^ (fig. 278, G, H), a Wealden 

 species recorded from Germany and England, represents a closely 

 allied or possibly an identical type. The section of the stem 

 (fig. H) shows the narrow vascular bands, x, of a dictyostele 

 similar to that of recent Cyatheaceous tree-ferns and a form 

 of meristele (fig. G, x) resembling that of P. punctata. 

 Adventitious roots are seen in section at R (figs. G and H). 



Polypodiaceae. 



Sections of petrified sporangia from the English Coal- 

 Measures (Pteridotheca sp.) occasionally exhibit a striking 

 resemblance to those of recent Polypodiaceae^, but in the 

 absence of material in which it is possible to recognise the 

 true orientation of the sporangia, the exact position of the 

 annulus is almost impossible to determine. We have as yet 

 no satisfactory evidence of the existence of true Polypodiaceae 

 in the Palaeozoic era. It is noteworthy that apart from the 

 absence of ferns which can reasonably be included in this family, 

 the anatomical features of the Botryopterideae (Coenopterideae) 

 and of the Cycadofilices or Pteridosperms do not foreshadow those 



1 Heer (75). ^ Heer (82) PI. xlvii. . 



3 Erie and Bayer (01) p. 76. 



* Stenzel (86). See also Stenzel (97). ' Gwynne-Vaughan (08). 



» Schenk (71) PL xxx. ; Seward (94=) A. PI. xi. ' Scott (08) p. 293. 



