450 



COENOPTEKIDEAE 



[CH. 



Metaclepsydropsis duplex closely resemble one another, draws 

 attention to certain differences in the structure of the xylem 

 which he regards as sufficient to justify a generic separation. 

 The leaf-traces of Clepsydropsis are described by Bertrand as 

 almost circular closed rings of xylem instead of an arc as in 

 Metaclepsydropsis. 



Fig. 310. A. Metaclepsydropsis duplex. 

 B, C. Stauropteris oldhamia. 

 D. Ankyropteris scandens. 

 tA, from a section in Dr Kidston's Collection (Lower Carboniferous); B, C, from 

 sections in the Cambridge Botany School; D, after Stenzel.] 



Ankyropteris. 



Stenzel adopted this name for a subdivision of Corda's genus 

 Zygopteris, applying it to a species described by Renault as 

 Z. Brongniarti, to a Permian species described by himself as 

 Z. {Ankyropteris) scandens, and to Z. Lacattii Ren.; Rachio- 

 pteris Grayi Will, and Rachiopteris corrugata Will, are also 

 included in this genus. The characters emphasised by StenzeP 



1 Stenzel (89) p. 25. 



