i i 
1906] JEFFREY & CHRYSLER—CRETACEOUS PITVOXYLA 5 
Fig. 4 shows the structure of the wood in the same specimen, 
as seen in tangential section under a low magnification. The rays 
are of the two kinds found in Pityoxylon Kraus, namely, linear and 
fusiform. 
Fig. 5 shows a tangential view of part of the same section, more 
highly magnified. In this view the radial pits of the tracheids may 
be seen in profile, and on the left a face view of a few tangential 
pits. In some of the rays dark contents may be made out in the 
cells, which have partially shrunk away from walls. This is appar- 
ently of the same nature as the dark brown material found in the 
resin cells of certain living conifers. The interesting fact to be 
noted is that the resin occurs equally in the marginal and in the 
central cells of the ray. This feature may be clearly distinguished 
in two of the rays on the lower left portion of the photograph. In 
living pines resin never occurs in the marginal cells of the ray, which, 
as is well known, are not true parenchymatous cells, but are of a 
tracheary nature. They are in fact variously described as mar- 
ginal tracheids, horizontal tracheids, and tracheidal cells. 
Fig. 6 shows another portion of the same section as that repre- 
sented in fig. 4, on the same scale of magnification as jig. 5. This 
figure shows very clearly the occurrence of tangential pits, which 
are confined to the autumnal tracheids as in certain living species 
of Pinus. In jigs. 5 and 6 may be seen fusiform rays containing 
horizontal resin canals occluded by tyloses. 
Fig. 7 represents a transverse section, under high power of mag- 
nification, of the autumnal wood of a specimen showing annual 
rings with a large radius of curvature. The elements are much 
larger in this instance, as is the rule in the older wood of the Conif- 
erales in general. The tangential pits of the autumnal wood can 
be very clearly made out. We have found no specimen of Pity- 
oxylon from the Kreischerville deposits in which the tangential 
‘pitting of the autumnal tracheids is not a marked feature. Con- 
WENTZ has pointed out that this feature is also present in the autumnal 
wood of the Baltic amber-producing trees (/..¢., p. 21). 
It will be inferred from the above description that the Cretaceous 
Pityoxyla just described differ in several features from the woods 
.of any modern or even Tertiary species of Pinus. The leafy short- 
