Jeffrey. — On the Structure of the Leaf in Cretaceous Pines. 21 1 
of the tracheids. This is the first occasion on which the author has 
observed this phenomenon, so common in living Conifers other than the 
Araucarineae, in a Mesozoic lignite. The entire absence of all indications 
of a transition towards the Araucarian condition of pitting in the oldest 
structurally known Abietineous Conifer furnishes a strong argument 
against the Abietineae having come from an Araucarian stock. On the 
other hand, in the wood of numerous species of the older Araucarians, 
which have been investigated for the first time structurally, in the case 
of leafy branches, by the author, there is a very marked departure from the 
Araucarian type of flattened or angular pits, towards the rounded bordered 
pits present in the remaining Coniferales, notably in the Abietineae. This 
transition towards the Abietineous condition in the radial pitting of the 
tracheids is paralleled by marked Abietineous characters in the wound re- 
actions, and in some cases by the ray structure found in the case of the older 
Araucarians of the Cretaceous. It may accordingly be stated, in passing, 
that there is much better anatomical evidence from the Cretaceous for the 
Araucarineae having come from the Abietineae than for the opposite view, 
which is implied by the hypothesis that the Araucarians are the most 
ancient of living Conifers. Further consideration of this subject may ad- 
vantageously be deferred % until the end of the article. 
Fig. 13, PI. XIII, is a magnified representation of a transverse section 
of a leaf resembling that of Pinus , which is considered, on grounds to 
be stated below, to belong to Prepinus statenensis. The contour of the leaf 
is very different from that found in any living Pine, for instead of having one 
curved face and one or two plane surfaces, as is the case in the fascicular 
leaves of Pinus , we find five approximately plane surfaces. Any departure 
from the planar condition is probably to be explained as the result of the 
vicissitudes accompanying fossilization. On the margins of the angular leaf 
are to be seen two resin-canals. The fibro vascular bundle is single, as in the 
sections Strobus , Cembra and Caryopitys , of living Pines, and entirely lacks the 
phloem, which has disappeared through decay. The bundle is bounded by 
a dark zone which completely surrounds it, the like of which has not been 
found in the fascicular leaf of any living Pine. Outside the dark sheath just 
mentioned is a thick zone of transfusion tissue, made up of coarsely pitted 
transfusion cells, without any admixture of parenchyma, such as is found 
abundantly in the tissues surrounding the leaf-bundle in living Pines. This 
entire exclusion of parenchymatous elements from among the short 
tracheid-like cells, which constitute the transfusion tissue, has an interesting 
parallel in the complete absence of parenchyma (exclusive of that found in 
the rays) in the secondary wood of the older Gymnosperms, and is probably 
in both cases to be regarded as a primitive feature. Another remarkable 
contrast with living Pines offered by our species is the absence of any 
indication of an endodermal sheath separating the bundle and its associated 
