MESOZOIC PLANTS FROM KOREA. 33 



and strong. Pinnae usually linear, subopposite, leaving the raeliis 

 at an angle of about 45° or more ; or, as is sometimes the case, 

 standing perpendicular to the rachis ; close together so as to 

 overlap in the posterior portion of the frond. Pinnules vary 

 considerably in size and form ; those in the posterior part being 

 generally very narrow, linear, often finger-shaped and falcate ; 

 decurrent at base, giving the rachis a slightly winged aspect ; 

 they are usually close together but sometimes quite remote from 

 one another ; serrate along the margin, the teeth gradually changing 

 into numerous small trigonal segments. Anterior pinnules close 

 together, varying in form from a short and more or less trigonal 

 one to lanceolate, with the front margin usually straight and the 

 back more or less strongly covex and with a bluntly pointed 

 apex ; attached by the whole of the broad base to the rachis. 

 Median vein well preserved, scarcely reaching to the summit of 

 the pinnule ; lateral veins very obscure, somewhat distant, oblique 

 and with single bifurcation. Sori large in proportion to the 

 pinnules, nearly round, very prominent, appearing as pustular 

 elevations on the upper surface ; crowded, arranged in a single 

 row on each side of the median-vein ; fertile pinnules somewhat 

 rolled up along the margin, with lateral veins quite obscure. 

 Even by Schulz e's method, it is not possible to determine the 

 character of the sporangia or the spores. 



Among the Japanese fossils, there are many forms, more or 

 less closely related to this Korean species. First of all, there is 

 Pecopteris exiliformis^^ of Geyler, who pointed out its close resem- 

 blance to P. exilis. Subsequently, however. Prof. Yokoyama"^ 

 considered this Scarborough species as itself represented in the 



1) Geyler: Pflanzen a. d. Juraform. Japans, p. 226, pi. XXX., fig. la. 



2) YoKOYAMA : Jurassic Plants, p. 35, pi. I., figs. 8, 10. 



