CERTAIN DICOTYLEDONOUS AND CONIFEROUS LEAVES. 255 
The epidermal cells between two stomata of a series have an average length 
of ‘032 mm. and an average width of ‘019 mm. 
Thus the ratio of length to width is 2:1. 
The epidermal cells between two linear series of stomata have an average 
length of ‘064 mm. and an average width ot ‘019 mm. 
Hence ratio of length to width is 3 : 1. 
SEQUOIA SEMPERVIRENS, Endl. 
External Characters. —The general appearance is very different from that 
of Sequoia giyantea or the fossil Araucarites Gépperti. The narrow oblong 
leaves spread outwards from the stem at an angle of 45°. The midrib is 
prolonged to form a short spine-like tip. Average length 1:8 cm. ; average 
width 2 mm. . 
This leaf has also been described by Rudolph Florin. 
Cuticular Structure (Pl. 91. figs. 26, 27).—Stomata occur on both upper 
and under surfaces, and are arranged in linear series which are grouped to 
form a wide band on either side of the midrib on the under surface, but the 
stomata are very few on the upper surface, three rows of widely separated 
stomata alone being found, and in one preparation only, while other pre- 
parations showed no stomata on the upper surface. 
Stomatal Apparatus.—The poral ring of subsidiary cells consists of com- 
monly four, less frequently five cells, and of these, those orientated vertically 
are much longer than those which close in the ring horizontally. The hori- 
zontally disposed cells serve in some cases as connecting cells between one 
stomatal pore and the next, and then are vertically or in some cases obliquely 
elongated. The vertical cells have one end produced in some stomata, 
beyond the other cells, forming horn-like projections. The long axes of the 
openings are vertical to oblique. 
Epidermal Cells.—The series of stomatal lines and epidermal cell rows are 
all curiously waved. This is due to the ring-like group of poral cells being 
large and causing the epidermal cells of either adjacent vertical line to curve 
round them. This wavy outline makes the cells difficult to measure. The 
cells, both between the individual stomata and between adjacent stomatal 
series, are mainly vertically elongated, though the ceil next to one of the 
poral ring and in a vertical line with it is sometimes longer horizontally. 
The cross walls of the cells are oblique and somewhat curved, not very 
angular. The cells between two different stomata of a series are much 
shorter and wider than those between two different stomatal series. The 
ratio of length to width is 2 : 1 in the former case and 7 : 1 in the latter 
case. The midrib is about 17 cells wide. Its cells are extremely long and 
narrow, with very oblique end walls ; ratio of length to width is 10 : 1. 
Upper Epidermis.—The whole preparation showed nine stomata in three 
wide apart serial rows. The poral rings are smaller than those of the lower 
