26 M. YOKOYAMA. 



185Ï, vol. VII. p. 179, pi. XII, fig. la, 11». 



Dicksonia clavipes — Heer, Beitr. zur Juraflora Ostsib. u. d. Amurl., 

 1876, p. 33, pi. II, tig-. 7, 71). 



On a small piece of sandstone from Shirnamura, there occur 

 fertile pinnae of a fern, which possess comparatively large, kidney- 

 shaped sori 1.5 — 2 mm in breadth, each of which is borne at the apex 

 of a shoit lobe 1 more or less narrowed towards the base. Under 

 a magnifier, a vein is seen u'oinu' into each sorus. sometimes giving off 

 delicate lateral veinlets (fig. la). 



These pinnae no doubt belong to a Dicksonia which is at least 

 very closely allied to D. clavipes Hr. from Kaja in Siberia (Beitr. 

 1876, p. 33). This latter species is considered by Prof. Nat h ors t as 

 identical with Sphenopteris ncphrocarpa Bunb. from the Oolite of York- 

 shire. To this opinion Heer assents in his Nachträge, p. 6. As I 

 see no sufficient character to separate the Japanese from the Siberian 

 fossil, I identify them, and following Heer (Nachtr., p. 6) in the 

 denomination of the species, I call it Dicksonia ncphrocarpa Bunb. 



S[). 



To this group may be referred the fertile pinnules figured by Old- 

 ham and Morris as Sphenopteris Bunburyana (The Flora of the BajmaJial 

 scries, pt. XXX J I tig. 5, 6', /), which Feistmantel includes, together 

 with our present species, under Hymenophyllites Gup. (Jurassic Flora of 

 the Bajmahal Group, p. 26-27). Loc. Shirnamura. 



3 Onychiopsis 



m. 



Fertile segments different from the sterile. Sori terminal, linear, 

 on each side of the midrib, parallel with the margin, involucrate ; the 

 involucrum of each side confluent over the midrib. 



This new genus, which I have founded on a plant first described 

 by Dr. Geyler under the name of Thi/Vsopieris elougata and afterwards 



