77 ° Jeffrey.—On the Affinities of the Genus Yezonia. 
cavities representing resin canals, may be seen a somewhat meandering 
zone of periderm. The general topography of this layer is shown more 
clearly in Figs. I and 4, PL 11, and Figs. 1 and 2, PL 12, of the joint memoir 
by Dr. Arthur Hollick and the writer, cited above. On the left of Fig. 11 
of the present article may be seen with particular clearness the radial rows 
of periderm cells. 
In Fig. 12, PL LXV, is shown a longitudinal section of the wall of the 
woody cylinder under a sufficient degree of magnification to indicate the 
height and position of the medullary rays of the wood. It is obvious that 
the latter are from one to two or three cells in altitude, precisely as in the 
description of the ray structure of Yezonia , Stopes and Fujii. The pitting 
in the tracheides of Yezonia also corresponds absolutely with that found in 
Br achyphy llum , for in both the pits occur in a single row on the radial wall 
of the tracheides. It has been observed in Br achy phy Hum, especially in 
older stems, that the pits are flattened by mutual contact, as in the Arau- 
carineae. This feature, however, is often not distinguishable in the wood 
of smaller twigs. 
The Anglo-Japanese authors attach considerable importance to certain 
features of the resin canals in the cortex of their genus Yezonia. They 
found, for instance, that there is frequently a layer of periderm present out¬ 
side the resin canals, which may in some instances invade the cavity of the 
canal itself. All these features are paralleled in Brachyphy llum , and are 
illustrated in Figs. 10 and 11 of the present article as well as in those of 
the large memoir cited above. They also emphasize the absence of any 
clearly defined epithelial layer around the secretory cavities or resin canals. 
A similar condition occurs in Br achy phy llum, as may be seen by examining 
the resin canals occurring in our Figs. 10 and 11. That resiniparous 
epithelial cells were really absent in the living plant is doubtful. It has 
been pointed out in an article written by Dr. Arthur Hollick and the 
present author 1 that the resin canals of Br achy phy llum, with a strong 
degree of probability, secreted both resin and mucilage, as is the case with 
the resin canals of Araucarian Conifers of the present epoch. The dark 
substance surrounding the resin canals in our Figs. 10 and 11, as well as the 
similarly indistinguishable cellular boundaries of the resin spaces described 
by Stopes and Fujii for their genus Yezonia , is in all probability of a mucila¬ 
ginous nature or represents a combination of limiting cells and mucilaginous 
contents. We have found a similar obscurity of the limiting layer of the 
resin canals in the cone-scales of almost all the Araucarian Coniferales from 
the Kreischerville deposits. This condition is shown particularly well in 
Figs. 1, 2, and 3, PI. 26, of our large memoir on the Conifers of Kreischer¬ 
ville. The feature emphasized by Stopes and Fujii has no special 
1 Affinities of certain Cretaceous Plants commonly referred to the Genera Dammam and Brachy- 
phy llum. American Naturalist, xl, pp. 189-215, 1906. 
