256 Mr Hamshaw Thomas, On some new and rare { 
On some new and rare Jurassic plants from Yorkshire :—_ 
Kretmophyllum, a new type of Ginkgoalian leaf. By H. HAMSHAW 
Tuomas, M.A., Downing College. Curator of the Botanical 
Museum, Cambridge. 
[Read 28 April 1913.] 
[Puates VI anp VII.] 
In the well-known Gristhorpe plant-bed, a number of isolated 
leaves occur, belonging to a type which has not been previously 
recognised. The plant-bed belongs to part of the Middle Estuarine 
Series of the Middle Jurassic and is exposed on the shore at the 
adjacent ends of Gristhorpe and Cayton Bays near Scarborough. 
I found most of my specimens in Cayton Bay, where they 
are locally plentiful. Two or three portions of leaves which 
appear to be closely allied to the Cayton forms have also been 
obtained from the Lower Estuarine beds at Whitby and though 
these exhibit some differences they may well be included in the 
same genus. All the leaves are beautifully preserved in shale, 
they were originally of firm texture and they can be readily 
detached from the shale, though the detached leaf is brittle and 
is easily broken into pieces. The examples shown in figs. 1 and 2 
Pl. vi. were detached from the rock, gummed on to glass and 
photographed by transmitted light. 
Description. 
The leaves from the Gristhorpe bed, which I propose to call 
Hretmophyllum* pubescens, vary somewhat in shape but are usually 
oblanceolate sometimes becoming almost linear. They may be 
straight but are often slightly falcately curved or at least un- 
symmetrical with one margin straight and the other curved — 
(cf. figs. 1 and 2). They are broadest towards the apex and taper _ 
gradually towards the base, the lamina passing into a broad — 
petiole of varying length. The leaves differ somewhat in size; — 
of the few complete examples the smaller are about 7 cms. long — 
and 1 cm. broad, the larger 10 cms. long and about 2°5 cms. broad. 
Fragments of leaves more than 3 cms. broad have been found, 
which, when complete, may have exceeded a length of 10 cms. 
The average leaf is about 17 cms. broad and 9°5 ems. long, — 
* From éperuovy =an oar or paddle and ¢¥\Aov=a leaf. Iam indebted to Miss W. 
M. L. Hutchinson for suggesting this name, 
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