The Philippine journal of science. [Vol. 57, no. 1]

57, 1

57, 1 ~Shapcarenko: Ginkgo Adictntoides 1

17

the only seemingly valid theory is that of a land connection then
existing between the continents. As may be seen by Wegener's
scheme there must have been an indissoluble connection between
these points, broken only in the Quaternary period when Greenland and North America were detached from Europe. One must
also take into consideration the propagation of the species in
unrelenting conformity with the zonal low towards the East
and South of the Angar center. No obvious change in the
meridional direction has been noted in the period between the
-4N'*#'*. ov? Me
PM oy"erw d ~srn ze C'.-'e'to'ceou-.
- Pfo9'e~sf O'4?547_9 zhe feovei.7e.
0.0 oG/J/0e9/ MO',#,6 O/'0oC*0e' - AtIVCde-7E0
o> 6'?*j0 OaseG / e&AvOpetO e-"O'0"410' APOb00,70 -FIG. 7. The distribution of Ginkgo adicantoideu Unger in different geologic periods. The
geographic network and the shapes of the mainlands are those of the Eocene. The
distribution was effected by means of the connections between continents. The map
shows the progress of distribution during the Jurassic, the Cretaceous, and the Eocene,
the region in which the plant was localized during the Oligocene-Miocene, the ginkgo
area which remained in Europe to the end of the Pliocene, and the Quaternary ginkgo
area.
Jurassic and the Cretaceous, and according to Wegener climate
changed very little during that time.
In the lower Tertiary we find the ginkgo in the region of its
primary center (Tschirimy-Kaja, Svalbard). According to Wegener the climatic changes to the Eocene on this part of the
40th parallel were insignificant as to cold (figs. 7 nd 8), which
may explain the growth of the ginkgo in the same area; it may
be slightly tending towards the Equator (seen on a contemporary
map to the south; Amagu River, Uglovaia Bay). One may
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