104 Fossil Wood and Lignites — Knowlton,. 
seemingly been greater and consequently the original outlines 
of the cells were more difficult of determination as they had 
been crushed and crowded upon one another in great confusion. 
A radial section shows the medullary rays to be in great 
abundance and, like the wood cells, to have been considerably 
distorted by pressure. In a few cases some of the cells of the 
rays were filled, before being subjected to this pressure, with a 
hard substance, which was more resistant to pressure, and con¬ 
sequently they retain nearly their original form. The number 
of cells entering into the composition of each ray varies con¬ 
siderably, ranging from as few as two or three, to as many as 
fifty or more. In most cases the rays are but one cell wood, 
although in a few cases sections have been obtained with the 
rays two cells wood. In one poorly preserved example there 
seemed to be several cells, perhaps as many as four, with a 
larger one in the center. This appearance may have been the 
result of pressure, and, if so, would have no value, but if 
natural it would indicate that the specimen belonged to the 
genus Pityoxylon. It is, however too indefinite to be more 
than suggestive. 
As for bordered pits or markings, they seem to have been 
pretty generally wanting, or at most rarely to have been pre¬ 
served in a satisfactory manner. They have been observed only 
in one instance, where only two pits or circular markings were 
noted 
In tangential section the medullary rays are seen to be very 
numerous, but this appearance is due partly to the collapsing 
•of the wood cells by pressure, by which they are made to occupy 
nearly one-third less space than when in a turgid condition, 
thus bringing a greater number of rays into the field at once. 
Most of the cells are crushed flat, only the one mentioned 
above escaping. 
In regard to the identification of this lignite it is manifestly 
impossible to attempt more than an indication of its general 
character and position. That it is coniferous is beyond question. 
The absence of cellular elements other than tracheds, which 
were provided in some cases at least, with borderered pits, and 
the number and arrangement of medullary rays, make the 
coniferous nature clear. From the abundance of the genus 
eupressinoxylon in the Potomac formation, as shown by the 
