MESOZOIC PLANTS FROM KOREA. 25 



those of 0. elongata sliows a slight difference in form. Tii the 

 former, the apical portion is nioi'e elongated while, in the latter, 

 it is usually rounded instead of being acuminated. 



However great the resemblance may be between the oriental 

 and the European species, the writer considers it at present proper 

 to keep them as two distinct species, as there are slight differences 

 in the form of the fertile pinnules and in the general habits of 

 the sterile joinnae. 



An examination of numerous figures of the species of Thyrso- 

 pteris described by Fontaine from the Potomac formation of 

 Virginia,'^ shows many forms moie or less closely allied to the 

 Japanese species. This fact was already pointed out by the author 

 of the Wealden Flora who placed T. rarinervis Fontaine among 

 the synonyms of 0. elo7igata. However, until a direct comparison 

 of the specimens from both sides is made, the question must be 

 left unsettled. Sewaed also compared Asplenium dicksonîanum 

 Heer^' from the Kome-beds of Greenland with the present species, 

 their external resemblance at least being very striking. Heer 

 placed the fossil under the genus Asplenvmn, because he was 

 convinced of its relation to the living Asplenium nigrum L.. 

 But there is no fructification to decide the question. 



Schenk"^' determined a specimen from Japan in one of 

 Richthofen's collections of fossil plants, as Thyrsopteris elongata 

 Geyler, to which Prof. Yokoyama and Seward also seem to 

 agree although the pinnules are apparently too broad to allow 

 this identification to pass unquestioned. It reminds some of 



1) Fontaine : Potomac Floni p. 123, pi. XXVI., figs. 6 & 7 ; pi. XLIII., figs. 4-6 

 pi. XLIV., figs. 1, 2, 5; pi. XLIX., fig. 2; pi. CLXIX., figs. 6, 4, 7. 



2) Heer: Fl. Foss. Arct., III., p. 31, pi. I. 



3) Schenk: Fossilen Pflanzen (Richthofen's China IV.), p. 26.3, pi. LIV., fig. 1. 



