THE CUTICULAR STRUCTURE OF CERTAIN LEAVES, 241 
A Preliminary Paper on the Cuticular Structure of certain Dicotyledonous 
and Coniferous Leaves from the Middle Eocene Flora of Bournemouth, 
By HELENA Banputska, A.R.C.S., M.Se.Lond. (Communicated by 
Dr. Marr C. Stores, F.L.S.) 
(PLATES 20 & 21, and 1 Text-figure.) 
[Read 18th January, 1923. ] 
INTRODUCTION. 
SiNCE very few Angiospermous fossils are preserved as petrifactions apart 
from secondary wood, we are very much at sea as regards the systematic 
position of most of the abundant and beautiful impressions of leaves which 
are so characteristic of some of the British Tertiaries. Although these 
Tertiary leaf-impressions and casts belong to a period too late to give us any 
clue as to the origin of Angiosperms, they show such enormous differences 
among themselves, that they should be of great value in determining 
problems of plant distribution, ete. once they can be definitely identified 
and compared. 
This paper describes Tertiary species which show cuticular structure, and 
although we cannot take anatomical evidence alone as a criterion of identity, 
we are justified in combining anatomical characters with external form for 
this purpose. Data obtained from externai form alone are extremely 
unsatisfactory, the task of identification being usually a hopeless one, for 
the variety of leaf-forms is apparently endless and the fossils so often fail to 
show any reliably distinetive features. 
In certain cases leaf-impressions possess a cohesive film censisting of the 
mummified cuticle of the leaf, which is capable of detachment by flaking off 
with a sharp knife. It is found then that while the internal cells always 
form a decayed mass, the more resistant external tissue persists uninjured 
and can be cleared by chemical means so as to reveal the cuticle in as perfect 
condition as though it were that of a plant existing to-day, and by this 
method data are yielded for comparison and identification. Leaves 
susceptible to this treatment are found in the Bournemouth floras, though 
in other Eocene floras the plants are usually not preserved in this mum- 
mified condition, hence the Bournemouth plants furnish a unique opportunity 
for anatomical investigations along these lines, and the present paper 
embodies some of this work. The material was partly collected by the 
writer in situ, some supplied by Dr. Marie Stopes from her collection, and 
the rest is contained inthe British Museum collection. The material collected 
LINN. JOURN.—BOTANY, VOL. XLVI. p 
