282 CORDAITEAE [CH. 



Niponophylhim. Stopes and Fujii. 

 Niponophyllum cordaitiforme Stopes and Fujii. 



The generic name Niponophyllum 1 was proposed for some 

 petrified specimens of leaves or possibly leaflets from Upper 

 Cretaceous beds in Japan which, though not definitely assigned 

 to a group or family, are considered by the authors of the genus 

 'to lie [anatomically] somewhere between Cordaites and Cyca- 

 deoidea' 'with a closer similarity to the former than to the latter 

 if we compare the whole Cordaites leaf with our blade.' The data 

 on which this conclusion is based are, however, insufficient to 

 justify a reference of Niponophyllum to the Cordai tales or indeed 

 to lend any substantial support to the opinion that the Japanese 

 specimens are anatomically more akin to Cordaites than to other 

 plants. The type-species is represented by two specimens of 

 leaf-fragments about 0*4 mm. thick and from 6 to 9 mm. broad 

 containing from 21 to 33 vascular bundles; the upper part of 

 the mesophyll is composed of palisade tissue and the stomata 

 appear to be confined to the lower epidermis. Each bundle is 

 accompanied by an I-shaped girder, and small patches of scleren- 

 chyma occur next the upper epidermis between the girders ; 

 there are no resin-canals: the vascular bundles are collateral, 

 the xylem is said to be almost entirely centripetal and exarch, 

 but in the absence of evidence afforded by longitudinal sections 

 the details of structure cannot be definitely determined. A com- 

 parison is made with Cycadean leaves and with leaves of Arau- 

 carineae and Podocarpeae, also with Cordaites] another type 

 with which Niponophyllum may be compared is Desmiophyllum 

 Solmsi 2 . 



The genus is interesting as an example of a petrified gymno- 

 spermous type of leaf characterised by the absence of resin-ducts 

 and transfusion-tracheids, the possession of collateral, apparently 

 exarch, bundles enclosed in a double sheath ; but the data supplied 

 are insufficient to enable us to allocate the specimens to a position 

 within the class. 



1 Stopes and Fujii (10) p. 16, PI. in. figs. 1416. 



2 See postea. 



