of the Anatomy of the Genus Selaginella , Spr. 175 
conditions still the steles of the branch and of the chief axis 
are united by metaxylem just at the point of union of branch 
and axis, but the united pair belonging to the chief axis 
separates again into two steles before the fusion with the 
conjoint steles of the branch. 
The stem is covered by a warty cuticle, epidermis, and, on 
an average, one layer of hypodermis, although this last is 
often wanting. The cortex consists of large delicate cells 
becoming smaller inwards and containing abundant chloro- 
phyll in the layers next the lacuna. The trabeculae consist 
of endodermal cells articulating with loose clusters of cells 
lying against the inner cortex. The lacuna is large and the 
steles are very loosely placed in it. There is indeed, as often 
as not, one (more or less constricted) lacuna containing both 
steles. The pericycle consists of one layer of large cells. 
There is one layer of sieve-tubes absent opposite the marginal 
protoxylems and separated by one layer of large-celled 
phloem-parenchyma from the xylem. The xylem is normal. 
39. Selaginella sulcata , Spr. Baker’s Handbook, No. 113. 
The stems of this trailing species are bistelic between 
branchings, but monostelic just beyond where a branch arises. 
The steles of the branch unite just previous to fusion with 
the stele of that side of the axis on which the branch is 
inserted. 
There is a small lumined epidermis containing red granules, 
a small amount of hypodermis, and a cortex, the inner layers 
of which are composed of cells whose walls are deeply pitted 
and connected at intervals with the cells belonging to the 
lacunar tissue. The trabeculae are simple and consist of 
single endodermal cells with the usual cuticular bands. The 
lacuna, however, contains a loose reticulum of creeping 
cylindrical cells arising at definite points and spreading in a 
radiating manner over the inner cortex (PI. X, Fig. 44). There 
are no cuticular bands on these cells. The stele consists of 
two to three layers forming the pericyle, a few crushed proto- 
phloem-elements, one or two layers of sieve-tubes — absent 
opposite the protoxylems — and two to three layers of phloem- 
