Seward: The Jurassic Flora of Yorkshire. 87 
garded as final. In all probability several species of the genus 
existed in the English Jurassic flora, but in view of the very con- 
siderable range in the degree of dissection of the lamina and in 
the size of the leaves of the surviving species (fig. 4), we cannot 
hope to define with accuracy the boundaries of the several 
species. The important fact is that Ginkgo leaves, resembling 
more or less closely those of the recent tree, as well as flowers and 
seeds, are represented in the Yorkshire Jurassic flora. Leaves 
with the Ginkgo habit, but with a more divided lamina are 
usually placed in the genus Baiera represented by the British 
Jurassic species described by the late Sir Charles Bunbury as 
Baiera gracilis. Other species of the genus have been des- 
cribed, and by many paleobotanists the common Jurassic 
genus Czekanowskia is considered to be another member of 
the group Ginkgoales, though the evidence for its close relation- 
ship with Ginkgo and Baiera is far from convincing. 
CONIFERALES. The interpretation of the frag xmentary 
records of coniferous twigs is often a well-nigh impossible task. 
Tempted by a resemblance in the form of the leaves, one is 
often inclined to assume a relationship with existing conifers 
which rests on wholly insufficient evidence. I would, however, 
refer more especially to a type of Jurassic Conifer from the 
Yorkshire rocks which can with confidence be assigned to a 
family position. Several years ago Mr. Carruthers described 
some seed-bearing scales in the Leckenby collection, which 
is one of the precious possessions of the Sedgwick Museum at 
Cambridge, as Avraucarites Phillipsi: these broadly triangular 
scales with a single median seed are practically identical with 
the cone-scales of some recent species of Araucaria. From 
the Jurassic beds of Stonesfield, from the Great Oolite of 
Northamptonshire, and from the Coralline Oolite of Malton 
portions of cones have been discovered which afford additional 
evidence of the existence of Araucarites in the Jurassic vegeta- 
tion. In all probability the common Jurassic conifer known 
as Pagiophyllum, or Elatides, Williamsoni represents the leafy 
shoots of an Araucarian plant, the form of the leaves being 
identical with that of the thick crowded leaves of the Norfolk 
Island Pine ( Avaucaria excelsa), and other species in the Aus- 
tralian region. Moreover from Upper Liassic beds at Whitby, 
petri ed wood was described as long ago as 1833 by Witham, 
shewing very clearly certain anatomical characters which enable 
us to identify the specimens as belonging to an Araucarian tree. 
It is clear that the genus Araucaria, now confined to a few 
regions in South America and to Australia, New Caledonia, 
and other islands was in the Jurassic era a common northern 
type. 
As yet no examples have been found in the Jurassic rocks 
of Yorkshire of any undoubted species of the Abietineae, the 
1gtt Feb, 1. 
