of the Anatomy of the Genus Selaginella, Spr. 183 
are often isolated parenchyma-cells scattered amongst the 
sieve-tubes (PL XI, Fig. 59). The steles (and especially the 
median one) are relatively broad and thin. 
45. Selaginella Willdenowii , Baker. Baker’s Handbook, 
No. 227. 
This well-known climbing species resembles anatomically 
X. inaeqnalifolia . The thick leafless lower stems are tristelic, 
as are also the terminal primary branches ; in the former the 
formation of accessory steles is much more common and 
extensive than in X. inaeqnalifolia (PL XI, fig. 62). From 
a comparison of the serial sections (PL XI, Fig. 61) it will be 
seen that there is a very close resemblance in the mode of 
fusion of steles in this species to that seen in the typical tristelic 
forms. Indeed, Fig. 61, PL XI, and Fig. 54, PL X, may be 
taken as, in most points, complementary to each other. 
The stem is as usual covered by epidermis and cuticle. 
The hypodermis varies in amount from two to twenty or more 
layers. The cortex consists of several layers of large cells 
followed by smaller cells towards the lacunae, where the 
innermost layers are loosely arranged. The trabeculae are 
either simple endodermal cells, or clusters of chlorophyll- 
bearing cells may occur round their distal ends. The pericycle 
is two to four layers deep, and encloses a small amount of 
protophloem. One to two layers of large lumined sieve-tubes 
surround the xylem, but separated from it by one to two 
layers of parenchyma. The sieve-tubes have both lateral 
and end plates. In many places, especially dorsally and 
ventrally, there is practically no lacuna, the pericycle being 
in contact with the cortex and destitute of endodermal 
cells. 
46. Selaginella canalicalata , Baker. Baker’s Handbook, 
No. 221. 
Not being possessed of much material of this species, 
I am unable to say whether the structure of the primary 
shoots agrees or not with that of the branches generally. 
The arrangement of the vascular system, however, in the 
latter agrees in all essential points with that in X. inaequali - 
