XL] 



GINKGOITES 



21 



acuminata^. A deeply divided obcuiieate leaf, only 2 — 4 cm. 

 broad, is figured by Dr Stopes^ from Jurassic strata (Lower Oolite) 

 on the Sutherland coast at Brora (fig. 635, J). The specimen 

 shown in fig. 633, also from the Sutherland coast, a few miles 

 north of Brora and of Kimeridgian age, illustrates the type of 

 leaf that may be conveniently referred to Ginkgoites digitata. 

 var. Huttoni^. Heer's Jurassic species. Ginkgo Jaccardi^, from 

 Switzerland is almost certainly Ginkgoites digitata. 



Arctic regions and northern Europe and Asia. 



The leaf reproduced in fig. 634 from a drawing made for me 

 in the Stockholm Museum through the kindness of Prof. Nathorst 

 was originally figured by Heer^ from Cape Boheman, Spitzbergen, 

 from beds assigned by Nathorst to the Upper Jurassic series. 

 Nathorst includes in this series strata agreeing in their fossil plants 

 with the Wealden of England and North Germany ; the ' Ginkgo 

 beds' may be Portlandian or even younger. The veins in this 

 specimen are approximately 1 mm. apart. 



The leaf represented in fig. 640 is one of several specimens 

 collected by Dr KoettUtz in Franz Josef 

 Land from beds that are probably Ju- 

 rassic. The lamina is 2-5 cm. in depth 

 and the veins are about 0-8 mm. apart i 

 the lamina between the veins shows a 

 fine transverse striation, not shown in 

 the drawing, a feature occasionally seen 

 in impressions of Ginkgoites and due in 

 all probabiUty to the shrinkage of the 

 mesophyll tissue into transverse bands^. 

 This form of leaf has been described as 

 Gingko polaris Nath.' ; it is smaller than most examples of Ginkgoites 



1 Seward (04) B. p. 98. 



2 Stopes (07) PI. xxvii. fig. 4. For a map of the Sutherland Coast, see Seward 

 (IP). 



3 Seward and Bancroft (13) p. 886. ' Heer (70) PI. lviii. fig. 20. 

 5 Heer (77) i. PL x. fig. 2. 



" For similar transverse wrinkling, see Schenk (71) B. PI. xxrv. figs. 7, 8; 

 Seward (11) PI. xi. fig. 74; Heer (77) ii, PI. xi. fig. 1 6. 



' Newton and Teall (97) PI. xxxviii. figs. 1, 2; (98) PI. xxix. fig. 3; Nathorst 

 (99) PI. 1. fig. 8 and Thomas (11) PI. iv. fig. 8. 



Fig. 640. Ginkgoites digitata 

 var. polaris. Franz Josef 

 Land. (Museum of the Geo- 

 logical Survey, London ; 

 nat. size.) M. S. 



