14 M. YOKOYAMA. 



gramme. It is moreover a very important fossil, occuring, as it does, 

 in all the fossil localities — except at Ushimaru where indeed very 

 few species have been found — especially at Shimamura, Okamigö 

 and Tanimura, where it is the most abundant of all. The other 

 genera of this order are Pccoptcris, Splwitopteris and Macrotaeniopteris. 

 The first is represented by two important species, Pecopteris exilis 

 and P. Saportana, both of which have been found in Spitzbergen ; 

 the former being originally described from Yorkshire. Splienop- 

 teris and Macrotaeniopteris are each represented by a single species, the 

 latter probably identical with the Chinese form M. Richthofeni. 



2. Rhizocarpeae. Represented by a single species of 

 Sagenopteris resembling very much Sagenopteris rhoifölia Presl of the 

 Rhaetic and Liassic of Europe. 



3. Equisetaeeae. Only two species of the genus Equise- 

 tum which are so far imperfect ; one of them however with tubers 

 preserved recalling those of recent species. 



4. Cyeadeaceae. These are nearly quite as numerous as 

 the ferns. They belong chiefly to the family Zamieae, the foremost of 

 which is Zamites parvifolius, so far a strictly Japanese species. The 

 genus with the greatest number of individuals is Podozamites, repre- 

 sented by at least 3 species. Of these P. lanceolatus with (> varieties 

 occurs plentifully at Shimamura and Okamigö. It is very important, 

 as it may be called almost cosmopolitan, being found in nearly all the 

 countries where Jurassic flora flourished. Another species of Podoza- 

 mites, viz., Podozamites tenuistriatiis, may be considered as a veay close 

 ally of P. lanceolatus, being quite like the latter in form, only with 

 finer veins. Very remarkable are the leaflets of P. Beinii which are 

 as numerous as those of P. lanceolatus. On the one hand it exhibits 

 nearly rounded leaflets, and on the other, very elongated ones, thus 

 affording passages to that cosmopolitan species through its variety 



