Bailey. — A Cretaceous Pityoxylon with Marginal Tracheides . 317 
Fig. 4 shows the tangential section under higher magnification, and 
illustrates with greater distinctness a portion of the structures shown in 
Fig. 3. It may be noted that the marginal cells of the linear ray in the 
central portion of the figure are narrower and devoid of resinous contents. 
Similarly, two cells of the next ray to the left are of small size and without 
the dark-coloured substance which fills the ray parenchyma cells. This is 
in marked contrast to the other Cretaceous Pityoxyla , especially Pityoxylon 
statenense and P. scituatense of Jeffrey and Chrysler, in which the marginal 
cells are not noticeably narrower than the central cells of the ray. In 
radial section the cells are seen to be ray tracheides, since bordered pits occur 
between adjoining cells of this form , and half-bordered pits between these cells 
and the succiniferous ray parenchyma cells. 
Fig. 6 shows in radial section a linear ray composed of succiniferous 
ray parenchyma and ray tracheides. The latter, which occur in the middle 
of the ray, are noticeably narrower than the ray parenchyma cells, and 
possess bordered pits between their end walls. The lateral pits of the ray 
parenchyma cells are seen with difficulty in this photomicrograph owing to 
the resinous character of the cells, but are narrow lenticular openings, with 
circular borders on the tracheide side. This type of pit, which occurs 
characteristically in all Abietineous Conifers with the exception of certain 
large pitted and highly specialized modern pines (see Figs. 11 and 12), has 
been conveniently called ‘piciform ’. In the Pityoxylon under consideration 
in this article, the pits, although variable in size and somewhat larger than 
the most primitive type (see Fig. 10), are uniformly distributed, one to each 
crossing field. Fig. 7, a radial section of the root wood of Finns Taeda , L., 
illustrates pits of similar size, shape, and structure, and in the central 
portion of the photomicrograph the distribution, one pit to each crossing 
field, is also similar. 
The sclerified condition of the pith is shown in Fig. 8, a longitudinal 
section of the small branch found embedded in the larger fragment of 
lignite. The clusters of sclerenchymatous cells are arranged in more or less 
well-defined horizontal bands. 
Fig. 9 shows a cross section, cut near the base of one of the brachy- 
blasts or short shoots. Clusters of sclerenchymatous cells, such as occur in 
the pith of the branch, are also present in the medullary tissue at the base 
of these structures. The short shoots are thicker and shorter than those of 
most species of living pines. 
The Identification of Coniferous Woods. 
With this consideration of the salient anatomical characters of the 
lignite, we may turn to a consideration of the affinities of the specimen. 
One of the earliest scientific classifications of coniferous woods, and one 
which in its main features has been adopted by most modern anatomists 
