400 
Stopes and Kershaw .— The Anatomy of 
The phloem is exceptionally well preserved for a fossil (see ph , Fig. 2, 
PI. XXVIII, and Phot. 4, PI. XXVII), and is relatively large in amount. 
This leaf comes much nearer the living type of Pinus than do any 
described by Jeffrey or Hollick and Jeffrey. Hence, as they use the generic 
name of the living forms for their species, there appears no excuse for our 
creating a new genus to include our species, though on the whole we are 
not in favour of using the same generic name for living forms and fossil 
fragments. Only where the fossil plant is approximately known in its 
entirety is it wise to include it in a living group. 
Our leaf, however, is so remarkably like the specialized and well- 
characterized Pinus leaf that the use of the modern generic name may 
be allowed. 
Pinus yezoensis, sp. nov. 
Leaf oval in outline, diameter about 1 mm. Central vascular strand 
large; radial wood strands separated by large rays; endodermal sheath 
very well marked; mesophyll with infolded walls; hypoderm slightly 
developed ; resin-canals two, laterally placed. 
Horizon.—Upper Cretaceous, Hokkaido (old Japanese name Yezo). 
Collected by M. C. Stopes. 
Type :—the figured slide has been presented to the British Museum, 
Department of Geology. 
Discussion .—The interest of this Cretaceous leaf lies in its complete 
likeness to the living types. Hollick and Jeffrey (’ 09 , p. 13), in speaking of 
their Cretaceous species of Pinus , remark that * these remains, when 
sufficiently well preserved, possess one feature which, in general, serves 
to distinguish all of the Cretaceous Pines thus far examined by us from 
those now living, and that is the very wide zone of transfusion tissue 
surrounding the leaf bundles. . . . The endodermal sheath separating the 
transfusion tissue from the mesophyll is also less clearly marked than 
in living Pines, or may be entirely absent.’ In Jeffrey’s (’ 08 ) fuller de¬ 
scription of the leaves (p. 216) he enumerates four points in which the leaves 
of true Pines of the Staten Island deposits differ from those now living. 
They are: (1) ‘In the better development of the transfusion elements 
round the bundle.’ Our new species, from the Japanese Cretaceous, has 
less rather than more transfusion tissue than is common in living Pines. 
(2) ‘In the differentiation of the transfusion elements into an inner sheath 
composed of elongated tracheidal elements, and an outer, much broader zone 
made up of more nearly isodiametric elements with thinner walls.’ The 
Japanese species does not show such differentiation. The few slightly 
sclerized cells above and below the bundle might possibly be considered as 
remnants of the inner sheath, but this theoretical view entails its application 
to living Pinus , which the new fossil species resembles in this feature. 
