CERTAIN DICOTYLEDONOUS AND CONIFEROUS LEAVES. 251 
uticular Structure of Araucaria excelsa (Pl. 20. figs. 17, 18). 
Stomata.—These are situated on the floor of fairly large pits, occurring both 
on upper and lower epidermis, and in bands parallel to the long axis of the 
leaf. A band consists of widening linear rows of stomata, two rows near 
the extreme apex, the number of the rows rapidly increasing from apex to base 
so that near the base there are five linear rows of stomata in a band. There 
are from 30-38 rows of epidermal cells in the middle of the leaf between the 
two stomatal bands of the leaf. In the fossil specimen, although the band of 
stomata widens slightly near the base, more than three linear series of stomata 
in a band have not been found, while at the extreme apex, one linear series 
only occurs. The guard cells of the stomata of A. excelsa are surrounded by 
four, more rarely five, subsidiary epidermal cells which occur above them, 
aud have slightly thickened inner walls and somewhat more thickened radial 
walls. The opening of the pore can be seen as a narrow, sharply angled slit, 
and the granular guard cells can also be seen. The subsidiary cell group is 
larger than in the fossil specimen. 
Epidermal Cells.—Two to three rows of epidermal cells occur between 
each linear series of stomata in a band; in places one row only occurs, 
owing to the somewhat irregular grouping of the stomatal lines. In the 
fossil there is commonly a single linear series of epidermal cells between 
two adjacent Jines of stomata in a band. Occasionally two or three rows of 
epidermal cells occur, especially passing towards the base of the leaf. In 
Araucaria excelsa the epidermal cells between the rows of stomata are 
elongated parallel to the long axis of the leaf, but between the stomata in 
a row they are somewhat elongated horizontally. The epidermal cells 
when seen with a low power appear to be straight oblong rectangles, 
but under a high power show distinct sinuations here and there. Thus 
one wall of a cell may be sinuate, the others almost straight, and this wavy 
wall may be a vertical or a cross wall. There may be a few sinuations 
only in the wail or they may be numerous. One cell showed one wall with five 
sinuses and another with three. One marked sinus in the cross wall is fairly 
common. Actual preparations show this better than the photographs do, 
for the sinuations in the photomicrographs are somewhat blurred. Simple 
pits seen on edge are very common and occur at the bases of the sinuses, 
which are, when present, much less deep than those of Araucaria Cun- 
ninghamii. The sinuations are narrow and shallow, and occur rather locally, 
and large parts of a field may show none. 
Cuticular Structure of Araucaria Bidwillii (Pl. 20. fig. 19, Pl. 21. fig. 20). 
Here the upper surface is practically destitute of stomata. The under 
surface bears linear series and the uniseriate rows are not grouped into 
bands. Two, three, or four epidermal cells intervene in linear series between 
adjacent stomata in a vertical row, and these are elongated in the vertical 
