60 



GINKGOALES 



[CH. XL 



Eretmophyllum saighanense (Seward). 



This species (fig. 658, A), originally referred with some misgiving 

 to Podozamites 1 and compared with Yokoyama's Ginkgodium, is 

 from Jurassic beds in Afghanistan. There can be little or no 

 doubt as to its generic identity with the Yorkshire leaves. The 

 broadly linear lamina tapers gradually to a slender petiole and the 

 veins, 1 mm. apart, are simple except at the proximal end. 



Mr Thomas is certainly justified in his opinion that Eretmo- 

 phyllum is a member of the Ginkgoales. In shape the leaves 

 resemble Ginkgodium and differ but little from some Jurassic 

 specimens referred to Ginkgoites. They agree in venation, in the 

 presence of short secretory tracts, in the structure of the epidermal 

 cells and stomata with Ginkgo and species of Ginkgoites. Eretmo- 

 phyllum is distinguished from Feildenia by its larger leaves, a 

 coarser venation, and a more definite petiole. Some leaves 

 figured by Fontaine 2 from Jurassic-Cretaceous rocks of Alaska 

 as Nageiopsis longifolia? Font, have little claim to be included in 

 that genus 3 and may perhaps be allied to Eretmophyllum. 



1 Seward (12) p. 35, PL iv. fig. 53. 



2 Fontaine in Ward (05) B. PL XLV. figs. 15. 



3 Berry (10) p. 190. 



