' 
258 Mr Hamshaw Thomas, On some new and rare 
type seen in some recent Ginkgo leaves. In the centre of each 
cell is a short but conspicuous papilla (cf. fig. 4) and the presence 
of these structures gives to the cuticle a very characteristic 
appearance. 
On the cuticle from the lower epidermis, the papillae are still 
more marked (fig. 3); the epidermal cells were again irregularly 
polygonal in shape. In these preparations we see the stomata 
very clearly, they are confined to the areas between the veins. 
The stomata are arranged in irregular rows and are easily dis- 
tinguishable on account of the thickened subsidiary cells. The 
guard cells do not seem to have been thickened and were somewhat — 
sunken, their outlines are now only indistinctly seen. Above and — 
around them lie the subsidiary cells (fig. 5) four to seven in 
number, regularly arranged and with clearly defined walls; they 
are more or less uniformly thickened and sometimes possess small 
papillae, they show more clearly after staining with Fuchsine. 
These stomatal structures show close resemblance to those of 
other Jurassic leaves allied to Ginkgo, and also to the stomata of 
the present-day leaves of this form*,; the recent stomata, how- 
ever, are less deeply sunken and not so much covered by the — 
subsidiary cells. 
The Whitby specimens. 
In one of the plant beds on the Scar at Whitby I have found 
several portions of leaves which seem to belong to this genus. 
The largest piece is about 7 cms. long, 12 mm. broad and slightly 
faleate; though neither end is seen, it tapers slightly above and 
below. Another well-preserved fragment belonged to a some- 
what broader leaf. The veins in these examples are about 1 mm. 
apart but do not clearly show any forking; a portion of one 
margin is slightly thickened as near the base of #. pubescens; 
secretory tracts have not yet been observed. The leaves were 
again stout and can be readily detached from the matrix. The 
epidermal structure of this form, which I propose to call #. Whit- 
biense, differs considerably from that of HH. pubescens. When 
viewed under the binocular microscope, the upper surface is seen 
to be rough, the individual cells being more or less visible as 
convex projections. The areas above the veins are distinguishable — 
by their more elongated cells but in addition to these, interstitial 
strands of elongated cells are seen between the veins, which 
sometimes appear to anastomose with each other, and may have 
corresponded with thickened hypoderm strands or small veins. 
* Cf. Seward (11), Pl. v. figs. 59-62. 
