of the Anatomy of the Genus Selaginella , Spr. 165 
The protoxylems are arranged as in S'. atroviridis. The 
stele is slender and covered by a pericycle usually one layer 
deep. The sieve-tubes are one layer deep followed by one 
layer of phloem parenchyma. There are usually two dorsal 
protoxylem-cords. 
30. Selaginella Bakeriana , Bail. Baker’s Handbook, No. 63. 
The arrangement of protoxylems in this species is some- 
what similar to that seen in S. atroviridis , save that the 
inner protoxylem of the chief axis, after becoming a dorsal 
cord, fuses with the outer protoxylem of the chief axis just 
before the origin of the next older branch of that side. 
Metaxylem is first developed just at the point of origin of 
branches where the leaf-trace of the axillary leaf is inserted 
(PI. IX, Fig. 22). The pericycle is two to three layers deep. 
There are a few protophloem-elements followed by the sieve- 
tube layer. The sieve-tubes are usually one layer deep, but here 
and there two and even three layers occur, especially between 
the dorsal protoxylems. The sieve-tubes are separated from 
the xylem by two to three layers of phloem-parenchyma. 
The sieve-tubes are absent opposite the marginal protoxylems. 
The inner cortex has a small amount of silica deposited on it. 
(PI. IX, Fig. 23). 
31. Selaginella concinna, Spr. Baker’s Handbook, No. 71. 
The protoxylems are arranged in this species almost as 
in 5 . Bakeriana . There is an epidermis, slight amount of 
hypodermis, and a large-celled cortex. The endodermal cells 
articulate with the swollen distal cells of the cortex. The 
pericycle is two to three layers thick. The sieve-tubes are 
arranged in a single or occasionally double layer, but are en- 
tirely wanting opposite the marginal protoxylems. They are 
separated from the xylem by two to three layers of parenchyma. 
The cortex has a siliceous deposit on its innermost cells. 
32. Selaginella uncinata , Spr. Baker’s Handbook, No. 58. 
In this species a slightly higher stage is reached in the 
evolution of the vascular system. An examination of a young 
erect shoot shows a ribbon-shaped stele with two marginal 
protoxylems formed by fusion of leaf-traces. At the origin of 
