SAGENOPTERIS 131 



Type. Detached leaflets of various shapes and sizes. 

 Dunker defines his species as follows 1 : 



" Cyclopteris fronde .... pinnis crassis subpetiolatis, oblique 

 cordatis vel cuneato-subrotundis vel ovato-obtusis integris vel sub- 

 crenatis, nonnullis apice sinuatis et bilotatis, nervis creberrimis 

 flabellatis apicem versus irregulariter dichotomis." 



The Wealden specimens enable us to give a more complete 

 diagnosis of the species. 



Leaf consisting of four leaflets sessile on the apex of the leaf- 

 stalk, palmately arranged, variable in shape and dimensions, the 

 two upper or terminal leaflets larger than the lower pair, spathu- 

 late, obovate or elliptical, margin entire, or with one or two broadly 

 rounded lobes. 



Venation reticulate, the meshes elongated in the direction of 

 the long axis of the leaf; in some leaflets there is a fairly distinct 

 midrib near the point of attachment, but it rapidly dies out 

 towards the apex ; in some specimens no sign of a midrib. 

 Fructification unknown. 



Dunker's figures 2 of detached leaflets, if we accept his view 

 that they all belong to the same species, sufficiently demonstrate 

 the wide limits within which their form and size vary. 



The small specimens figured by Ettingshausen 3 agree much 

 more closely with Aneimidium Klipsteini (Dunk.), and, indeed, he 

 includes that species as a synonym of Sagenopteris Mantelli (Dunk.). 

 Possibly, as suggested in the above list of synonyms, one of the 

 leaflets is that of the present species, but it is by no means certain 

 that any of them should be included under the genus Sagenopteris. 

 Schenk 4 points out the close connection between Sagenopteris 

 Mantelli (Dunk.) and S. rhoifolia, Presl; it seems, indeed, almost 

 impossible to draw any distinct line between these two species. 

 As a rule the leaflets of the former are smaller and less elliptical 

 or elongated than those of the latter, but it is quite conceivable 

 that the discovery of more Wealden specimens may compel us 

 to recognize more definitely this close agreement between the 

 two forms. 



1 Wealdenbildung, p. 10. 



2 Loc. cit. pi. ix. fig. 4. 



3 Abh. k.-k. geol. Reichs. vol. i. Abth. iii. No. 2, p. 13. 



4 Palseontographica, vol. zix. p. 223. 



