-3 M. YOKOYAMA. 



PI. II). The pinnules are much elongated, being longest near the 

 base of the pinna. They are quite entire in the upper pinnae, but 

 become lobed as they get downward, and the incision between the 

 lobes becomes deeper and deeper, so that at last the individual lobes 

 look quite like the pinnules of the upper part of the frond. Fig. 3, 

 PI. II, represents a pinna belonging to the lower part of the frond, 

 whose extremely elongated pinnules give such an appearance as above 

 alluded to; fig. 3a is an enlarged view of a part of one of them. 

 The length of a pinnule here attains about 37 mm, the breadth being 

 only 3 mm. Fig. 10, PL II also represents an inferior pinna. 



Along with these sterile pinnae are found fertile pinnules which 

 are either borne quite on a separate pinna or, as is sometimes the case, 

 mixed with the sterile pinnules (comp. fig. 1, 4 a, b, PI. II, fig. 6d, 

 PI. Ill, fig. 9, PL XII). The sori -are placed two at the end of each 

 pinnule which is considerably narrowed looking like a winged stalk. 

 These double sori are opposite, elongated, linear, meeting each other 

 along the midrib. 



This splendid fern is the chief and characteristic fossil of the 

 Japanese flora, being found in all of the fossil localities. 



4. Adiantites Gap. 



9. Adiantites Heerianus m. 

 PL XII, fig. 1, la. lb, 2 



Pinnae elongated; pinnules alternate, acutely directed forward, 

 rhomboidal, attenuated'^ below, acute at apex, acutely lobed ; veins equal, 

 fine, repeatedly dichotomous 



The four pinnae shown in fig. 1 and 2, 1 believe, to belong together. 

 The pinnules are, as a general rule, obliquely rhomboidal in shape, 

 attenuated towards the base, and acutely pointed at the apex. They 

 are mostly acutely lobed, but becoming entire and more lanceolate in 



