136 Gibson . — Contributions towards a Knowledge of 
15. S. denticulata, Lk. 
Ventral leaf. Ovate, somewhat cordate, faintly spiny. Stomata 
occur on the aligular surface only, over the midrib and wings ; a few 
occur near the margins. 
Dorsal leaf. Similar in shape to the ventral, but smaller ; faintly 
spiny. Stomata occur on both sides, 
Section. As in the type. 
16 . S. patula, Spr. (Fig. 11.) 
Ventral leaf. Lanceolate, oblique, abruptly pointed, with marginal 
trichomata at the base, spiny at the apex. Stomata occur along the 
edge of the ligular surface where the ordinary polygonal cells of this 
surface become longer. The aligular cells (Fig. n) are partly 
sclerotic, and each bears one or two rows of cuticularized warts. 
The cells are shorter over the midrib where the stomata occur. 
Dorsal leaf. Leaves ovate, cuspidate with marginal trichomata. 
Stomata occur on the ligular face near the base. The aligular 
epidermal cells are warty. 
Section. As in the type. 
17. S. eonvoluta, Spr. 
Ventral leaf. Oblique sickle-shaped, acute, with spiny margins ; 
the lamina near the margins one cell thick. The aligular surface only 
bears stomata. 
Dorsal leaf. Ovate, oblique, acute, with spiny margin. Both 
ligular and aligular surfaces bear stomata. The cells of the aligular 
face are, in most parts of the leaf, nearly as long as those of the 
ligular surface. 
Section. Reticulate mesophyll between the two epidermal surfaces, 
but the upper cells (ligular) are closely packed and form a pseudo- 
palisade-layer. Dangeard speaks of stomata on the ligular as well 
as on the aligular face of the ventral leaf. As I have above stated, 
this is true of the dorsal leaf (which Dangeard does not refer to in 
this relation), but I have been quite unable to find stomata on the 
ligular face of the ventral leaf. 
18 . S. flabellata, Spr. 
Ventral leaf. Oblique ovate, bluntly pointed, faintly spiny along 
one side. On both ligular and aligular surfaces the epidermal cells 
vary in length. 
