XL] BAIBRA 37 



phyllum. There are, liowever, certain Permian leaves that are 

 legitimately included in Baiera; the genus appears to have been 

 widespread in Triassic floras, though more especially in those of 

 the Rhaetic and Jurassic age. Baiera shares with Ginkgoites an 

 important position in the Jurassic vegetation of both hemispheres, 

 but in the Cretaceous period Baiera appears to have been a com- 

 paratively rare genus and in the Tertiary floras it was entirely 

 replaced by members of the Ginkgoales with leaves of the type 

 that still survives. Baiera is clearly an older form than Ginkgoites ; 

 it is not recorded from India and it has not been found in the 

 Permo-Carboniferous rocks of Gondwana Land. 



Baiera though unknown in a petrified condition nday con- 

 fidently be included in the Ginkgoales ; the habit of the leaves, 

 the structure of the epidermal cells and such evidence as there is 

 with regard to the fertile shoots favour this conclusion. It must, 

 however, be added that the position of the Palaeozoic examples is 

 less firmly estabhshed. 



Baiera virginiana Fontaine and White. 



This species, from Permian beds in Virginia^, is based on im- 

 perfect portions of laminae deeply divided into bifurcate segments 

 with trtmcate apices and several parallel veins ; it agrees in the 

 form of the lamina and in the hnear divisions with the type- 

 specimen of Brongniart's Fucoides digitatus^ from Permian beds 

 of Mansfeld, a species which Geinitz^ also recorded, but under the 

 generic name Zonarites. Potonie* and other authors, following 

 Hear, transferred the species to Baiera. Heer's combination, 

 B. digitata, had, however, already been used by Schimper^ for the 

 Jurassic species iisually called Ginkgoites digitata. 



Leaves of the form represented by B. virginiana may be closely 

 allied to Saporta's Permian species Ginkgophyllum (PsygmophyUiim) 

 Grasserti^. In the absence of the basal part of the lamina a com- 

 plete diagnosis or accurate identification is impossible. Some 

 .authors have referred fragments of similar leaves to the genus 



» Fontaine and White (80) B. p. 103, PI. xxxvii. figs. 11, 12. 



2 Brongniart (28^) A. p. 69, PI. ix. fig. 1. 



3 Geinitz (62) PI. xxxi. figs. 1, 2. 



« Potonie (93) A. p. 237, PI. xxxn. fig. 2 ; PI. xxxm. fig. 6. 

 5 Sohimper (69) A. p. 423. « Page 87. 



