14 GINKGOALES [CH. 





is unfortunate, but whether or not Shirley's fossil is identical 

 with Saporta's specimen there would seem to be no reasonable 

 doubt that it should be included in the genus Ginkgoites. 



Fig. 632 B is drawn from a photograph of a specimen in the 

 Brisbane Museum which I recently had an opportunity of examin- 

 ing: it is from the Ipswich beds and is undoubtedly specifically 

 identical with Saporta's type. 



from 





Ginkgoites digitata (Brongniart). 



This widely spread Jurassic species founded on leaves fr 

 the Yorkshire coast, was first figured by Phillips in 1829 1 as 

 Sphenopteris lalifolia, but under the same name Brongniart 2 had 

 a year previously recorded a Carboniferous Fern. In 1830 Bron- 

 gniart 3 figured and described another Yorkshire specimen as Cyclo- 

 pteris digitata : the generic name Cyclopteris was adopted by Bunker 

 and other authors until Heer 4 drew attention to the very close 

 agreement between the Jurassic leaves and those of the Maidenhair 

 tree, a similarity that led him to adopt the generic designation 

 Ginkgo. Leaves hardly distinguishable from the Jurassic impres- 

 sions had previously been recorded from Tertiary rocks as species 

 of Salisburia or Ginkgo. 



It is impossible to define precisely the several species of Gink- 

 goites founded on leaves : in the account of the recent species 

 attention is called to the range in leaf -form and its bearing on 

 the determination of fossils. All that can be done is to adopt 

 certain specific names as a matter of convenience, recognising 

 that the differences on which the classification is based are not 

 either sufficiently sharply defined or morphologically important 

 to be regarded as criteria of true specific distinctions. Many 

 authors have employed the specific name Huttoni, first used by 

 Sternberg 5 , for leaves identical in size and outline with G. digitata 

 but characterised by a deeply-lobed lamina; this difference is, 

 however, not greater than or even as great as differences met 

 with within the species Ginkgo biloba. To facilitate description 

 the designation Huttoni is retained as a form- designation for the 

 more deeply lobed examples included in the species G. digitata (e.g. 



1 Phillips (29) A. PI. vii. fig. 18. See Fontaine in Ward (05) B. p. 121. 



2 Brongniart (28) A. p. 51. 3 Brongniart (28 2 ) A. p. 219, PI. LXI bis, figs. 2, 3. 

 4 Heer (81 2 ); (77) i. p. 40. 5 Seward (00) B. p. 256. 



