TRANSACTIONS OF SECTION K. 709 
lacunz in the ground tissue. Clearly allied to the P. reticulatum of Unger. 
Whether a Pteridosperm or a Fern cannot be determined. 
6. Stereopteris annularis, gen. et sp. nov. 
A petiole, with a single large vascular bundle, somewhat resembling that of 
Clepsydropsis or Asterochlana in form, but with solid wood, and external 
protoxylem. Cortex differentiated into several distinct zones, 
Probably a Fern, with some affinity to the Zygopterider. 
7. Lepidostrobus Fischeri, sp. nov. 
One of the oldest known fructifications with structure. The axis is of an 
ordinary Lepidostrobus type, the sporangia have the usual columnar wall, and the 
spores are in tetrads. 
A full account of these fossils will shortly be submitted to the Royal Society. 
2. On a New Type of Ginkgoalian Leaf. 
By H. Hamsuaw Tuomas, M.A. 
In the Jurassic plant-bed of Cayton Bay, near Scarborough, a number of 
beautifully preserved leaves occur which belong to a new type. They are linear 
or oblanceolate in shape, with rounded or slightly bifurcated apices, short 
petioles, and dichotomising venation. The leaves are usually found in a 
mummified state; they can be readily detached from the rock, and yield 
beautiful cuticular preparations. The form of the stomata and subsidiary 
cells is very similar to that of other Ginkgoalian leaves, while they possessed 
the secretory. tracts between the veins as seen in the modern form. The 
epidermal cells possess very characteristic papille. 
These leaves form the type of a new genus Hretmophyllum with two species, 
a second form having been found at Whitby. The specimens provide a further 
illustration of the importance of the Ginkgoales in the Mesozoic vegetation, 
while they are an example of the interesting preservation of some Yorkshire 
plants and of the importance of the study of cuticular structure. 
3. A New Species of Medullosa from the Lower Coal Measures. 
By EH. ve Fraine, D.Sc. 
The specimen consisted of a short length of stem surrounded by adherent 
leaf-bases, and occurred in a coal-ball obtained from the Lower Coal Measures 
of Lancashire. 
The stem was of small size, the diameters of the transverse section being 
only 5 cms. X15 em., including the leaf-bases. 
The vascular system of the stem consisted in the upper sections of three 
irregularly shaped outer steles, roughly triangular in outline; one of these steles 
branched during the length of stem available so that the lower sections of the 
series show a ring of four steles. The outer ring of steles encircles a small 
central strand or ‘ star ring,’ which undergoes no change during the series, and 
forms the characteristic feature of the fossil. A narrow zone of periderm en- 
closed the vascular tissues of the stem. 
The numerous leaf-traces passed out from the peripheral parts of the outer 
steles. The leaf-bases showed a typical Myeloxylon structure with numerous 
exarch collateral bundles and abundant gum canals, and the hypoderma was of 
the Myeloxylon Landriotii type. In the general structure of the steles and 
of the leaf-bases and in its histological details the stem shows a very close 
resemblance to Medullosa anglica. 
4. The Pinna-Trace in the Filicales. 
By BR. C. Davin, M.A., B.Sc. 
There are two main types of vascular supply to the pinne in the Filicales. 
The ‘marginal’ type occurs generally from leaf-traces which have no hooks 
at their ends; the ‘extramarginal’ appears regularly in connection with leaf- 
traces possessing incurved hooks. The ‘marginal’ type is found, however, in 
