XXl] GLEICHENIACEAE 353 



Leuthardt^ figures what appears to be a Gleicheniaceous 

 fern from the Upper Triassic beds of Basel as Oleichenites gracilis 

 (Heer) showing sori composed of five sporangia (fig. 265, C) 

 with a horizontal annulus. A Rhaetic species Oleichenites 

 microphyllus Schenk^ from Franconia agrees in the form of its 

 small rounded pinnules with Gleichenia, but no sporangia have 

 so far been found. 



An impression of a frond from Jurassic rocks of northern 

 Italy figured by Zigno as Oleichenites elegans^ closely resembles 

 in habit recent species of Oleichenia; though no sporangia have 

 been found, the habit of the frond gives probability to Zigno's 

 determination. 



A Jurassic species from Poland, Oleichenites Rostafinskii, 

 referred by Raciborski* to Oleichenia, exhibits a close agree- 

 ment in habit and in the form of the soral impressions to some 

 recent species of Oleichenia. 



As we pass upwards to Wealden and more recent rocks it 

 becomes clear that the Gleicheniaceae were prominent members 

 of late Mesozoic floras in north Europe and reached as far north 

 as Disco Island. In English Wealden beds portions of sterile 

 fi'onds have been found which were assigned to a new genus 

 Leckenhya^, but it is probable that these specimens would be 

 more correctly referred to Oleichenites. Similarly fragments of 

 Gleichenia-like pinnae with very small rounded pinnules occur in 

 the Wealden rocks of Bemissart, Belgium', in north Germany '^, 

 and elsewhere. Conclusive evidence has been obtained by 

 Prof Bommer of the existence of Oleichenites in Wealden beds 

 near Brussels, where many plant remains have been found in a 

 wonderful state of preservatien. The specimens, which I had an 

 opportunity of seeing some years ago, might easily be mistaken 

 for rather old and brown pieces of recent plants. Some of the 

 Belgian fragments, of which Prof Bommer has kindly sent 

 me drawings and photographs, are characterised by an arrange- 



1 Leuthardt (04) p. 40, PI. xviii. fig. 3. 



2 Sohenk (67) A. p. 86, PI. xxii. figs. 7, 8. 



3 Zigno (56) A. PI. x. 



1 Kaoiborski (94) A. p. 43, PI. xiii. figs. 15—20. 



= Seward (95) A. p. 225. « Seward (00) PI. iv. ' Schenk (71). 



