322 Holden. — On the Anatomy of 
of the greater part of each tracheide, but towards the ends it is often 
replaced by the more crowded position which obtains in other Araucario- 
xyla. In the photograph, Fig. 31, PI. XX, the small size of the pits is very 
striking, but it seems probable that the state of preservation somewhat un- 
duly accentuates this appearance. Examination of a number of slides has 
revealed a few places where the structure of the pit is perfectly retained. 
From these it is evident that originally they were closely compressed and 
flattened where in contact ; the outside of the border was angular, while 
the actual opening was an elliptical slit. Further, as in all Palaeozoic 
woods, there was probably no torus. During the process of fossilization, 
the aperture was enlarged until it has become circular, the inner margin of 
the border was darkened so that it now appears as a black rim, while the 
outer, originally angular, margin is indistinguishable. Gothan 1 figures a 
specimen where a similar darkening of the inside of the border, coupled with 
the obliteration of the outside, causes the pits to appear more remote than was 
actually the case. Tangential sections indicate that this interpretation of 
the structures in question is the correct one. The beaded appearance of 
the wall (Fig. 22, PI. XX) is due to the fact that the entire border has 
disappeared, leaving a much enlarged aperture to represent the former 
extent of the whole pit. Nevertheless, by actual measurement, the size of 
the pits is extraordinarily small. Gothan (1. c. p. 20) gives the dimensions 
of a number of typical Araucarioxyla varying from 16 /x in diameter in 
A . Kenperianus to 8-9 /x in A. Tchihatcheffianns\ and it is noteworthy that 
in this Indian specimen the pits are smaller still, having an average 
diameter of only 4 /x. 
The medullary rays (Figs. 2 and 4, PI. XVII) present nothing of especial 
interest. They are always uniseriate, and in height range from 1 to 20 cells, 
with an average of 6 to 7. The walls are thin and unpitted, except where in 
contact with tracheides. Here the pits are in groups of 2 to 7 to each cross- 
field ; they are small, half bordered, with an elliptical aperture. It might be 
suggested that the groups described above as characteristic of the radial 
walls of the tracheides are really caused by rays which crossed at these 
points, and that the pits in question are not those from tracheide to 
tracheide, but from tracheide to ray. It is true that the structure and 
mode of occurrence are similar, but the fact that the groups on adjoining 
tracheides are not on the same horizontal line indicates that this explana- 
tion is not the correct one. Further, tangential sections (Fig. 4) show 
conclusively that the grouping on the tracheides bears no relation to the 
presence or absence of rays, and that the pits are really from tracheide to 
tracheide. 
Having completed the description of this fossil, it is apposite to consider 
its relation to other similar specimens. The absence of primary tissue 
1 Gothan (1905). 
