CH. XLIl] GINKGOPSIS, NEPHROPSIS 77 



GINKGOPSIS. Zalessky. 



This generic term proposed by Zalessky 1 for Schmalhausen's 

 Ginkgo Czekanowskii, but not defined by him, may be adopted for 

 certain leaves resembling those of Ginkgo but which there is no 

 adequate reason for regarding as the leaves of a member of the 

 Ginkgoales. 



Ginkgopsis Czekanowskii (Schmalhausen) and Ginkgopsis minuta 

 (Nathorst). 



The small leaves, or leaflets, described by Schmalhausen 2 from 

 the Permian of the Lower Tunguska river as Ginkgo Czekanowskii 

 are more or less orbicular and the lamina, approximately 1-5 cm. 

 broad, is divided into several bilobed segments (fig. 664, C). It 

 is by no means certain that all the fragments included in this 

 species are specifically identical; some bear a close resemblance 

 to Ginkgo minuta Nath. 3 from the Rhaetic of Scania, a type which 

 he assigns with hesitation to Ginkgo and compares with the leaves 

 of Acrostichum peltatum. It is impossible without additional data 

 to determine either the systematic position of the specimens 

 included in these two species or their morphological nature. 

 Through the kindness of Prof. Zalessky I have been able to examine 

 photographs of some of the original material and, as shown in 

 fig. 664, C, the supposed leaves are borne on a rachis-like axis, 

 possibly of some Pteridosperm, a circumstance which though not 

 proving that they are leaflets of a compound frond, favours that 

 interpretation. 



NEPHROPSIS Zalessky. 



This name is proposed by Zalessky 4 for the leaves described by 

 Schmalhausen and Renault respectively as Ginkgo integerrima and 

 Ginkgo martensis on the ground that these Permian specimens do 

 not afford satisfactory evidence of close affinity to the genus 

 Ginkgo. The two sets of leaves are probably specifically identical. 



Nephropsis integerrima (Schmalhausen). 



In fig. 664, A, B, are reproduced two of the leaves from the 



1 Zalessky (12 2 ) p. 28 (footnote). 



2 Schmalhausen (79) A. p. 84, PL xvi. figs. 810. 



3 Nathorst (86) p. 93, PL xra. fig. 112; PL xx. figs. 1416. 



4 Zalessky (12 2 ) p. 28 (footnote). 



