XL] 



GINKGOITES 



19 



occasionally occur iu association with the foUage of this and otbe; 

 Jurassic species. Male flowers^ similar in habit to those of Ginkgo 

 bildba are also found in beds containing impressions of Ginkgoites. 



The abundance and wide geographical range of Ginkgoites 

 digitata precludes anything more than a brief reference to some 

 representative types selected in illustration of the range in form 

 and the widespread occurrence of the species in Jurassic floras. 



The leaf represented in fig. 637 is an unusually complete 

 example from the Middle Jurassic beds of Scarborough ; the lamina 

 is 3-8 cm. deep and 6 cm. broad, 

 the venation agrees with that of 

 Ginkgo hiloba. A very similar type 

 of leaf is figured by Heer from 

 Upper Jurassic (or Wealden) strata 

 of Spitzbergen as G. integriuscula^, 

 but with the proviso that it may 

 be merely a variety of G. digitata, 

 a view that Nathorst^ has wisely 

 adopted. The latter author in 

 spealdng of the occurrence of G. 

 digitata in Spitzbergen states that 

 'sometimes the surface of the schists [shales] is as completely 

 covered with the leaves of Ginkgo as the soil beneath a living 

 Ginkgo tree may be in autumn*.' In some specimens from 

 the Yorkshire coast the lamina is practically entire as in a leaf 

 from Scarborough in the York Museum figured in 1900^. An 

 exceptionally large form is shown in fig. 638 ; the lamina, 8 cm. 

 broad, is divided into several short and comparatively broad 

 obtuse or truncate lobes*. Fig. 639 shows a leaf from the 

 Stonesfield Slate, now in the Cirencester Museum ; the lamina is 

 deeply divided into two broad cuneate lobes as in some forms of 

 the recent species. The Stonesfield Slate specimens were origin- 

 ally named by Buckman Noeggerathia {1) and later Stricklandia 



1 See page 51. 2 geer (77) i. p. 44, PI. x. figs. 7—9. 



' Nathorst (97) p. 1.5; for a discussion of the age of the Spitsbergen beds, see 

 JSTathorst (IS^). 



« Nathorst (11') p. 221. 



° Seward and Gowan (00) B. PI. x. fig. 54. 



« Seward (00) PI, II. fig. 5. 



2—2 



Fig. 637. Ginkgoites digitata. 

 (f nat. size.) M. S. 



