34 GINKGOALES [CH. 



some of his figures : these interstitial ' veins ' probably mark the 

 position of hypodermal strands of stronger cells, a feature that is 

 not represented in recent or fossil Ginkgo leaves and is by no means 

 generally characteristic of Baiera. Both Braun and Heer describe 

 male and female reproductive organs: Braun interpreted some 

 small specimens as sporocarps but these were recognised by 

 Schenk as young foHage leaves. The male organs are described 

 by Heer as 'amenta staminif^ra pedunculata, nuda, filamenta 

 fihformia, antherae locuhs 5 — 12, verticillatis. Semen drupae- 

 forme, basi cupula carnosa cinctum' and compared with Schenk's 

 Stachyofitijs Preslii which that author afterwards regarded as 

 microstrobili of Baiera Muensteriana. Reference is made to 

 these and similar fossils in the account of examples of male 

 flowers^. Seeds have been referred to Baiera on evidence 

 furnished by their occasional association with leaves and by their 

 resemblance to those of Ginkgo. It has been suggested that 

 specimens described from the Potomac group of Virginia and 

 Maryland as Carpolithus ternatus^ and other species may be seed- 

 bearing organs of Baiera, but there is no satisfactory evidence in 

 support of this view. In all probabihty some of the associated 

 seeds belong to Baiera, also some of the microstrobih, e.g. Leuthardt's 

 Swiss specimens described on a later page, but in the present 

 state of our knowledge it is preferable to regard these specimens 

 as reproductive organs that cannot be assigned with certainty to 

 any particular species of Baiera or Ginkgoites. 



Leaves assigned to Baiera vary within wide limits as regards 

 size, the number of linear segments and their angle of divergence. 

 In many cases the leaves are petiolate though in several instances 

 the petiole is represented by a narrow basal region of the lamina 

 as in Psygmophyllum. It is stated by some authors that the veins 

 are undivided, but though dichotomy is less frequent in Baiera 

 and may be absent in narrow parallel-sided segments it is by no 

 means rare. The difference in venation between such leaves as 

 Ginkgoites digitata and typical species of Baiera, e.g. Baiera gracilis, 

 is mainly the result of the different form and degree of dissection 

 of the lamina. The choice between Baiera or Ginkgoites as the 



1 Page 51. 



2 Fontaine (89) B. pp. 265 etc., Pis. 134 etc.; Berry (11) p. 372. 



