the Anatomy of the Genus Selaginella , Spr. 137 
Dorsal leaf. Similar in shape to, but one-third the size of, the 
ventral leaves. The stomata which occur only on the aligular face 
are frequently sclerotic. 
Section. As in the type. Dangeard’s figure of the transverse 
section of the leaf (/. c., Plate XI, Fig. 20) shows no intercellular 
spaces. This is quite incorrect. 
19. S. produeta, Bak. (Figs. 5, 6.) 
Ventral leaf Cordate, oblong-lanceolate, unequal-sided, with 
sclerotic margins, faintly spiny at and near the base. The aligular 
epidermis consists of the usual elongated wavy-bordered cells, with 
many sclerotic fibres interspersed. The stomata are almost all 
sclerotic (Fig. 5), the lumina of the surrounding epidermal cells being 
sometimes almost occluded. The epidermal cells also have numerous 
irregular thickenings on the lateral and end walls (Fig. 6). 
Dorsal leaf. Similar to those of the ventral side, but cuspidate. 
The aligular and ligular epidermal surfaces are similar to those of the 
ligular and aligular surfaces of the ventral leaf respectively. The 
stomata, which occur on the aligular face only, are sclerotic. 
Section. As in the type, save that the mesophyll-cells are very 
long. 
20. S. bisulcata, Spr. 
Ventral leaf. Oblique, ovate, bluntly pointed with spiny margin. 
The ligular epidermis bears numerous marginal stomata from base to 
apex. The margin has a warty sclerotic border. Stomata occur over 
the entire aligular surface. 
Dorsal leaf. Oblique, ovoid, cuspidate with spiny sclerotic margins. 
Stomata occur only on the aligular surface. 
Section. As in the type. 
21. S. uncinata, Spr. (Figs. 12, 13.) 
Ventral leaf Leaves oblique, oblong, subsessile, with quite smooth 
(n on-hairy) but sclerotic margins. Stomata occur on the aligular face 
only, the guard-cells having two large chloroplastids in each. 
Dorsal leaf. Ovate, with smooth sclerotic margin. Stomata on 
the aligular face only. 
Section. As in the type. 
The development of the stomata is discussed in Sect, II. 
