184 Atkinson . — A Monograph of the 
the enlargement. Sometimes near the base of the sexual 
shoot the band is interrupted, so that the antheridia are in 
spots, but they are not elevated on papillae, and by examin- 
ing the entire length of the plant the bands in the middle and 
terminal region will be found almost universally complete h 
For this group Sirodot retained the generic name Lemanea. 
If in some cases an external examination fails to reveal 
satisfactory characters for the determination of the two sub- 
genera, a microscopic examination of the internal structure 
will furnish the evidence. 
The sexual shoot is hollow, or tubular, containing a system 
of delicate filaments, the apparatus of fructification, which 
will be described after explaining the structure of the walls 
that protect the internal organs and give strength to the 
plant. 
Structure of the wall of the sexual shoot. The wall is more 
or less cartilaginous in nature and is composed of three 
different kinds of cells arranged in three layers. The medul- 
lary layer (inner layer) is composed of a single layer of com- 
paratively large cells, 40 \x. to 70 in diameter (Figs. 14 /, 
and 32). The cells vary from irregularly oblong to oval and 
spherical, are hyaline, possessing very little endochrome. The 
endochrome is arranged in small plates on the inner periphery 
of the cells. The intermediate layer is composed of some- 
what smaller cells, polyhedral in form and containing a little 
more endochrome. The cortical layer is composed of pris- 
matic cells, quite small, arranged parallel to each other and 
standing perpendicularly to the intermediate layer. The cells 
of the cortical layer are very rich in coloring matter. In some 
species, especially of the subgenus Lemanea , at maturity, the 
cortex is composed of two or three layers of cells (Figs. 41, 
L. australis , n. sp. and 46, L. grandis). 
Fig. 32 represents a longitudinal section of the sexual shoot 
of Lemanea australis Atk. at the period of fertilization. It is 
sufficiently clear to show the three different layers with their 
1 One species described by Sirodot, Ann. d. Sci. Nat., loc. cit., Z. parvula , 
belonging to this group, had the bands generally interrupted. 
