[PENHALLOW] A REPORT ON FOSSIL PLANTS 295 
it was impossible to identify it with any previously recognized fossil 
type, or with any existing species, although it is of interest to find that 
it is a hard pine of the general type of P. glabra, to which it some- 
what closely approximates, but from which it differs materially in the 
structure of the medullary ray. In the collections of 1905, from 
the same locality, precisely the same wood was once more brought under 
my notice, being recognized under the designation = . This more 
recent material, however, has been found to be in a much better state 
of preservation, conditions of decay not having progressed so far as 
in the previous case, and it therefore served to complete the diagnosis 
with respect to several important characters which were either wholly 
wanting in the previous material, or imperfectly presented. 
There is no record of the wood of Pinus having been found in 
the same horizon in North America, though Knowlton has described two 
species from the Laramie of the Vellowstone National Park, under 
the names of Pityoxylon aldersoni and P. amethystinum (35)  Bo- 
tween these and the present specimens, however, there are no points of 
resemblance. The diagnosis for the present species is as follows :— 
PINUS COLUMBIANA, n. sp. 
Plates III and IV. 
T'ransverse.—Growth rings variable though generally very broad in the large stems. 
Spring wood usually predominant, the transition to the summer wood 
gradual, but in the narrow rings more or less abrupt and sometimes 
conspicuously so; the tracheids large, thick-walled and often cons- 
picuously so, definitely rounded, often radially oval, chiefly uniform, 
more or less equal, in regular radial rows. Summer wood con- 
spicuous, dense and often thin. The structure as a whole is that of 
a rather dense wood of medium hardness. Medullary rays prominent, 
not very numerous, resinous and distant upwards of 9 or more rarely 
15 rows of tracheids. Resin passages conspicuous, rather large and 
scattering throughout the growth ‘ring, the parenchyma cells large, 
thin-walled and in two rows, or forming large, irregular tracts up- 
wards of 6-9 tracheids wide; resinous; thyloses not obvious. 
Radial.—Medullary rays resinous; the tracheids rather numerous, marginal and 
interspersed, not obviously predominant, very variable and often as 
high as or higher than long, sparingly dentate’; the parenchyma cells 
all of one kind and rather thin-walled, straight and equal to about 4 
wood tracheids, the upper and lower walls strongly pitted, the terminal 
walls straight or diagonal and apparently not pitted, the lateral walls 
with simple, round or lenticular pits of medium size, 2-4, chiefly 2 per 
tracheid. Bordered pits on the tangential walls of the summer 


1 Possibly due to conditions of decay. 
See. IV., 1907. 18. 
