124 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



ORDER GINKGOACE^ 



GINKGO SIBIRICA Heer 



Plate XIII, Figs. 1-4; Plate XIV, Figs, i, 2 



Ginkgo sibirica HEER, Fl. Foss. Arct, vol. 4, 1878, Abth. 11, p. 61, pi. vn, 



fig. 6; pi. ix, fig. 5/; pi. xi. 

 Baiera brevifolia Newberry, Am. Jour. Sci., 3d ser., vol. 61, 1891, p. 199, 



pi. xiv, fig. 3. 



The present collection contains such a bewildering array of ex- 

 cellently preserved Ginkgo leaves that I am almost at a loss to know 

 how best to dispose of them. Individual specimens can be so satis- 

 factorily matched with various described forms that it would be 

 little trouble to recognize perhaps as many as four or five so-called 

 "species" ; but no one who has examined a good series of leaves from 

 a tree of the living species (G. biloba) can fail to recognize the dan- 

 ger in this genus of basing species too closely on size, shape, or the 

 degree of lobation. In fact, it has been said that every described 

 fossil species of Ginkgo can be very closely approximated by leaves 

 from the living tree, and from evidence that has been accumulating of 

 late there is every reason to believe that the extreme variation now 

 exhibited has been a character of Ginkgo since its establishment. It is 

 of course true that a few dominant forms of types can be recognized, 

 and these may be — probably correctly — accepted until we have 

 secured collections of a sufficient magnitude to permit the working 

 out of the limits of legitimate specific variation. 



It is with some hesitation that I have decided to refer these leaves 

 to Ginkgo sibirica of Heer. The types of the species described from 

 the Jurassic of eastern Siberia are rather more deeply lobed than 

 the Kootanie specimens in hand, though they agree very well with 

 leaves that have been subsequently referred to it, such, for instance, 

 as the leaf figured by Saporta l from the Jurassic of France, and 

 it is certainly the same as the leaf from the Canadian Kootanie 

 figured by Dawson 2 under this name. In the same publication Daw- 

 son has also noted the presence of Ginkgo lepida, G. nana, and Baiera 

 longifolia; but, judging from the figures alone, it is very doubtful if 

 these can be maintained ; certainly the specimens referred to Ginkgo 

 lepida and Baiera longifolia must be identical, while his G. nana is 

 probably the same, though it is too fragmentary to be positive one 

 way or the other. 



1 Pal. Franqaise, PI. Jurass., vol. 3, pi. xxxn, fig. 6. 



3 Trans. Roy. Soc. Canada, vol. 4, sec. iv, 1885, p. 8, pi. 11, fig. 1. 



