1906] JEFFREY & CHRYSLER~—CRETACEOUS PITYOXYLA Il 
This species of Pityoxylon is named Pityoxylon scituatense, from 
its place of origin. The diagnosis is as follows: 
Transverse.—Annual rings moderately broad, indistinctly marked; resin 
ducts present, surrounded by a very deep zone of resiniferous parenchyma, 
without tyloses but sometimes filled with dark resinous contents; wood paren- 
chyma quite absent; rays very dark and resinous; tracheids averaging 39 u 
in diameter. 
Radial.—Radial pits of the tracheids in a single row with the very oblique 
narrow mouths forming a cross, diameter of the pits about 20 4; pits of the ray- 
cells generally one per tracheid with narrow oblique mouth, about ro # in diam- 
eter; ray-cells all parenchymatous, average length 340 #, very resinous; marginal 
ray-tracheids quite absent. 
Tangential.—Rays of two kinds, linear and fusiform, the former often very 
deep; fusiform rays containing horizontal resin canals, which are always free 
from tyloses although somewhat thin-walled, both kinds of rays very resinous; 
tangential pits present in some of the tracheids. 
In the two species of Pityoxylon described above, we have to 
do with woods which resemble those of the existing pines, but which 
nevertheless differ from them in important particulars. The mar- 
ginal ray tracheids, which are not only characteristic of Pinus but 
of the allied genera Picea, Pseudotsuga, and Larix, are quite absent 
in our two species. The question arises whether it is proper to 
include them within the genus Pityoxylon, which has recently been 
stated not to antedate the Tertiary.‘? There is much to be said 
for such a course. In the case of our Pityoxylon statenense there 
can be no reasonable doubt that we have to do with the wood 
of a fossil species of Pinus, from the abundant occurrence in 
intimate association with the lignites of charred remains of cone 
scales and leaf fascicles of pines. Any doubt as to the identity of 
these scales and foliar shoots has been removed by a study of their 
microscopic structure, as well as their external features. Further, 
one of us has observed from the study of the cones of living pines 
that the features which are characteristic of our fossil woods are 
exactly those which are found to be distinctive of the wood struc- 
ture of the cones of the living species of Pinus. There can be little 
doubt that in the case of the wood of the cones of Pinus palustris, 
for example, the general absence of marginal tracheids, the highly 
resinous character of the rays, and the abundant presence of tan- 
12 GOTHAN, /. ¢., pe 88. 
