20 ART. 8. — H. YABE. 



The genus was first established by Prof. Yokoyama iii 1890 

 for the reception of Thyrsopteris elongaia Geyi>er from the 

 Japanese Jurassic, on account of the close resemblance of its 

 fertile as well as sterile pinnae to those of the living species of 

 Onychium. Immediately afterward, Nathorst^' pointed out the 

 great similarity of Velonowsky's figures of the fertile frond of 

 Thyrsopteris capsulifera to the Japanese species, which fact led 

 him to bring it under the same genus, and he further proposed 

 to assign the well known European Wealden species — Sphenopteris 

 Mantelli Brongn. — to the same genus, which closely resembles 

 0. elongaia. This view was subsequently verified by Seward,"^' 

 who examined fertile pinnae of Sphenopteris Mantelli from the 

 British rocks and confirmed Prof. Yokoyama's view, that the 

 features of the fossil fern show a closer relationship to Onychium 

 than to any other living genus. 



Saporta^^ however on examining a fertile frond from Portugal 

 was inclined to bring the position of Sphenopteris Mantelli under 

 the genus DavaUia or at least into the group of the Davalliae. 

 But, Seward's words^' about this run as follows : " The compari- 

 son made by Yokoyama in the case of Onychiopsis elongata and 

 by myself as regards 0. Mantelli, w^ith the recent genus Onychium, 

 is, I belive, a much nearer approach to the truth than if we 

 ado]3t the conclusions of Saporta."^^ 



The genus has a wide range from Jurassic through Wealden 

 to Cenomanian ; altogether 4 species being known at present. 



1) jSatiiokst: lleitiilge z. Mesozoischen Flora Japaiis. 1S90. 



2) Seward : AVealden Flora I. 1894. P. 43. 



8) Sapokta : Flora Fossile du Portugal. 1894. 



4) Sewabd : Wealden Flora II., p. 229. 



5) The fertile fronds of Sphenopteris Manidll described by Satokta from the lower 

 Cretaceous of Portugal appear to tlie writer somewhat diflerent from those of the same 

 species from Yorkshire and also of Onychiopsis elon<jula. 



