IN THE STRATA OF THE CARBONIFEROUS SERIES. 41 



regular series of hexagonal cellules, separated at intervals by narrow spaces, 

 resembling separations of the walls of two contiguous series of cellules. 



Fig. 9- Represents a portion, magnified in the same degree, of the mar- 

 ginal part of the tissue, in which the same appearances are seen. The dark 

 lines are not medullary rays. There are no concentric lines to be seen. 



Fig. 10. Is part of a longitudinal section, more highly magnified, of the 

 same portion as that represented by Fig. 8. The cellules here also are very 

 regular, straight, and parallel. At first sight they might be taken for spiral 

 vessels, on account of their beautifully regular transverse linear markings ; 

 but, as it is found that the whole tissue of the plant presents the same ap- 

 pearance, and that these transverse lines are in fact delineated on the walls 

 of those tubes, of which the transverse sections are presented in Figures 8. 

 and 9 ; we must admit that the elongated cellules of the woody fibre of this 

 plant, instead of being marked with reticulations, as in the genus Pinites, 

 or with series of more or less separated areola^ as in the genus Pitus, are 

 characterized by very regular transverse lines. Some of these transverse 

 lines are connected by lines placed at right angles, but this reticulated ap- 

 pearance is of rare occurrence. 



Fig. 11. Represents part of a longitudinal section, magnified in the 

 same high degree as Fig. 10, of the portion represented in its transverse sec- 

 tion by Fig. 9- It exhibits precisely the same appearance. Figs. 10. and 

 11. are from slices cut parallel to the medullary rays, and therefore present 

 the markings of those sides of the elongated cellules, which are opposite to 

 the intercellular spaces, seen in Figs. 8. and 9. 



Fig. 12. Shews the appearance of the walls of the cellules facing the 

 pith on the one hand, and the surface of the plant on the other. These 

 walls are marked in precisely the same manner. The section of a medullary 

 ray is also seen in this figure. The medullary rays of this plant are so 

 small, and placed at such distances from each other, that one might be very 

 apt to overlook them, and transverse sections of considerable extent might be 

 made without any of them occurring in it. However, I have fully satisfied 

 myself that they exist. 



