of the Anatomy of the Gemis Selaginella, Spr. 167 
B. Oregana Type . 
33. Selaginella oregana , Eat. Baker’s Handbook. No. 7. 
This and the succeeding species are characterized by the 
possession of homophyllous leaves, but nevertheless a ribbon- 
shaped dorsiventral stele. 
X. oregana resembles in habit a Lycopodium and is found 
hanging in dense tufts from N. American forest-trees in a man- 
ner similar to that shown by certain species of that genus. It 
possesses a ribbon-shaped stele with two marginal protoxylems. 
The inner cortex shows four equidistant leaf-traces, and the 
outer cortex four more alternate with the inner ones (PI. IX, 
Fig. 30). These traces are not, however, inserted all round the 
stele, but on the marginal protoxylems only. The traces of 
the leaves which come off opposite to the margins of the stele 
pursue a curved course, but in the plane of the long axis of 
a section of the stele until, lower down, they become inserted 
on the marginal protoxylems. The traces of those leaves which 
arise dorsally and ventrally (with regard to the stele — for the 
stem itself is not dorsiventral) curve round in the cortex (and 
partly also in the pericycle) until, lower down, they in turn 
come opposite to the marginal protoxylems on which they 
are inserted. X. oregana thus forms a transition between the 
distinctly dorsiventral types, such as the majority of the 
monostelic Selaginellas, and the homophyllous radially sym- 
metrical type like S. spinosa , where the stele, at least in its 
upper parts, is cylindrical and has several protoxylem areas 
arranged round it. 
There is a large peripheral development of sclerenchyma, 
and the inner cortex consists of tubular cells with intercellular 
spaces, but without a siliceous deposit. The pericycle is from 
three to five layers deep. The sieve-tubes are in one or two 
layers and dorsiventrally flattened. They are absent opposite 
the marginal protoxylems, and, in the older stems, the dorsal 
and ventral (re stele) layers are frequently incomplete. One 
to two or more layers of parenchyma separate the sieve-tubes 
from the xylem. 
