of the Anatomy of the Genus Selaginella , Spr. 159 
broken dorsally and ventrally as well. One to two layers 
of parenchyma separate the sieve-tubes from the xylem. 
15. Selaginella involvens , Spr. Baker’s Handbook, No. 204. 
The dorsal cord in this species soon fuses with the 
marginal protoxylem. There is an ill-defined epidermis and 
a plentiful development of stereome. The cortex is composed 
of thick-walled tubular cells, with intercellular spaces in which 
an abundant deposit of silica occurs (PL IX, Fig. 17). The 
inner layers are loosely arranged and continuous with cells 
which articulate with the short endodermal cells. The stele 
is convex dorsally and flat ventrally, and composed of a two 
to three layered pericycle of small cells, one to two layers of 
sieve-tubes absent opposite the marginal protoxylems and 
separated from the xylem by, on an average, three layers 
of parenchyma. 
16. Selaginella cuspidata, Lk. Baker’s Handbook, No. 213. 
The arrangement of the leaf-traces and protoxylems is of 
the usual type. The stem has externally a cuticle, epidermis, 
and three to five layers of sclerenchymatous hypodermis. 
The cells of the inner cortex are small, loosely arranged, and 
have a siliceous deposit in the minute intercellular spaces. 
The trabeculae are not numerous and consist of endodermal 
cells articulating with the loose creeping inner cortical cells. 
These cells are full of starch and chlorophyll. The pericycle 
is as a rule one layer thick, though here and there on the 
dorsal and ventral surfaces it is double. One layer of sieve- 
tubes occurs dorsally and ventrally, but they are absent 
opposite the marginal protoxylems. The phloem-parenchyma 
is three to four layers deep. Amongst the scalariform tracheids 
there occur shorter elements with irregular reticulate thicken- 
ings. 
1 7. Selaginella molliceps , Spr. Baker’s Handbook, No. 325. 
The arrangement of protoxylems is normal. There is 
a cuticle, large- celled epidermis, but almost no hypodermis. 
The inner cortical cells are loosely arranged, those next the 
lacuna being swollen and articulating with the endodermal 
cells. The lacuna is large and the stele lies loosely in it. 
