24 M. YOKOYAMA. 



are acutely directed forward like the lobes themselves. A fragment 

 from Tanimura (PL XI, fig. 7) with acutely directed, in some cases 

 irregularly lobed pinnules very probably belongs to the some species. 

 The generic position of this fern is at present uncertain; but the 

 general aspect of the pinnules, and their mode of lobing remind us of 

 many of the Thyrsopteri which are widely spread in the Jurassic 

 system. Rare. Loc. — Shimamura, Tanimura. 



2. Dicksonia L'Herit. 



4. Dicksonia gracilis Heer. 

 PI. I, fig. 5, 5a. PL XII, fig. 13. 



Dicksonia gracilis — Heer, Beitr. zur Juraflora Ostsib. u.d. AmurL, 

 1876, p. 92, pi. XVII, fig. 3., Beitr. 1878, p. 13, pi. Ill, fig. 8-14. 



The specimens from both localities represent the upper part of 

 a frond. Although they are rather imperfect, and the impressions 

 more or less indistinct, yet the thickly-set narrow pinnae, with small, 

 broadly lanceolate, oblique, entire-margined, rather acutely pointed 

 pinnules, tend more to point to D. gracilis than to its close ally D. 

 acutiloba Hr. Heer speaks of his gracilis as having obsolete and aca- 

 tiloba distinct venation. Just so in our specimens ; the venation 

 is in most cases very indistinct. By strong enlargement, however, we 

 can observe faint undivided secondary veins rising acutely from the 

 fine median vein, as shown in fig. 5a. 



This species seems to have been very rare. Loc. — Shimamura, 

 Okamigö. 



5. Dicksonia acutiloba Heer var. 

 PL I, fig. 2a, 2, lb. 



Dicksonia acutiloba-Heev, Beitr. zur Juraflora Ostsib, u. d. AmurL, 

 1S76, p. 92, pi. XVIII, fig. 4. 



