86 Seward: The Jurassic Flora of Yorkshire. 
-Though our knowledge of the Jurassic Cycads from the 
Yorkshire coast is still far from satisfactory, we are justified 
in asserting that plants of this class played a prominent part 
in the Jurassic vegetation; they were represented by species 
of Otozamites, Ctenis, Nilssonia, and other genera. 
GINKGOALES (Ginkgo and Bavera). The Maiden-hair tree 
of China, Ginkgo biloba, so named by Kaempfer in 1712, and 
needlessly renamed by Smith in 1797 Salisburia adiantifolia, 
though well known in cultivation in Asia, Europe, and America, 
is probably extinct in a wild state. It was formerly included 
with the Yew as a member of the Taxeae, but since the Japanese 
botanist Hirase, in 1897, revealed the important fact that the 
male cells of Ginkgo are spirally coiled motile bodies, like those 
of the Cycads and comparable with the male cells of ferns, 
it has been customary to exclude Ginkgo from the Coniferae, 
and to consider it as the sole representative of the group 
Ginkgoales. Before Hirase’s discovery it was recognised that 
in several respects Ginkgo differed from the Taxeae and other 
Conifers, but it was his researches that furnished the strongest 
reason for the institution of a special group. The Maiden- hair 
tree, now regarded in the East as a sacred plant and cultivated 
in the groves of temples, is a solitary survivor of a group of 
Gymnosperms which had an almost world-wide distribution 
during the Jurassic era. ‘An old Oak,’ wrote Robert Louis 
Stevenson in his ‘ Inland Voyage,’ ‘that has been growing 
where it stands since before the Reformation, taller than many 
spires, more stately than the greater part of mountains, and 
vet a living thing, liable to sickness and death, like you and me, 
is not that in itself a speaking lesson in history ? But acres and 
acres full of such patriarchs contiguously rooted, their green tops 
billowing in the wind, their stalwart younglings pushing up 
about their knees—a whole forest, healthy and beautiful, 
giving colour to the light, giving perfume to the air; what is 
this but the most imposing piece in Nature’s repertory ? ” 
The contemplation of a living tree of Ginkgo biloba makes 
our minds reel in their fruitless attempts to grasp the full 
meaning of the antiquity of which it is the embodiment. The 
Maiden-hair tree, which, so far as we know, has persisted with 
but slight modifcation though successive «ons, bridges across 
the enormous gulf between the present and a past inconceivably 
remote. In 1828 Brongniart described some fossil leaves from 
the Yorkshire coast as Cyclopteris digitata, and in the following 
year Phillips spoke of the same type as Sphenofpteris latifolia, 
both authors regarding the impressions as those of a fern. 
Subsequently the true nature of the fossils was recognised, 
and they were referred to the genus Ginkgo. It is futile to 
attempt a specific separation of the numerous forms of Ginkgo 
leaves met with in a fossil state, which can confidently be re- 
Naturalist, 
