Sykes and Stiles.—-The Cones of the Genus Selaginella. 525 
means so prominent as in some others of the species examined. The spo¬ 
rangium originates (Fig. 2, PI. XLI) from stem tissue, and though it later 
becomes associated with a so-called sporophyll, it is never in this species 
placed accurately in its axil, but is always borne on the stem some little 
way above the axil (Fig. 3, PI. XLI). 
The sporophyll is shortly stalked, and, in addition to the large, upward 
extending portion of the lamina, there is a downward growing dorsal flap 1 
(Figs. 1 £, c, 2, 3, PI. XLI). The upper portion folds round, and to some small 
extent protects the sporangium associated with it. The dorsal flap protects 
the sporangium which occurs vertically below the sporophyll, 1 and a groove 
is also present in the sporophyll stalk into which this sporangium fits 
(g, Figs. 1 c and 4, PI. XLI). Fig. 4, PI. XLI, represents a tangential section 
through the cone of S. pumila , and clearly shows the relative positions of 
sporangia arrd sporophylls. 
The line of dehiscence of the sporangium is displaced slightly downwards 
towards the subtending sporophyll; dehiscence thus occurs in the position 
which in this species best ensures the liberation of the spores opposite the 
narrow gap between the sporophylls (see Fig. 3, PI. XLI), at the point 
most convenient for their dispersal. There is some feeble lignification at the 
base of the ligule. 
It may be of some interest to note that small projections occur on the 
dorsal surface of the lowest whorl of sporophylls forming the cone, although 
below these there are of course no sporangia (Figs. 1 and 1 a , PI. XLI). 2 
No such down-growths are developed in connexion with the vegetative 
leaves. 
The stalk of the sporophyll contains no air space, unless we should 
include in this category a very minute space sometimes found accompanying 
the stele for a short distance on its lower side ( a , Fig. 3, PI. XLI). 
X. rupestris is the only other form which has yet been described whose 
sporophylls are similar to those of X. pumila. In the cone of this species 
also, according to Lyon, 3 a large dorsal flap is present, which protects the 
sporangium vertically below it. The whole sporophyll here appears to be 
composed of loosely arranged tissue containing numerous intercellular 
spaces. 4 
It is interesting to find that these two species are placed near one 
1 The arrangement of sporophyllsand sporangia in this cone forcibly recalls Lycopodium cernuum 
(Sykes, M.G., 1908 (2),pp. 48-9; Lang, W. H., 1908) ; the sporophylls are perhaps even more strictly 
comparable with those of L. alpinum (Sykes, M. G., 1908 (2), p. 48, Fig. 8 a and b, PI. II). 
2 In S. Preissiana Goebel found that the lowest sporophylls resembled the foliage leaves instead 
of being intermediate in character, as in this species (Organography, ii, p. 506). 
3 Lyon, F., 1901, Fig. 124, PI. IX. 
4 Miss Mitchell (1910, p. 21) refers to the presence of a ‘strongly recurved portion ’ of the 
sporophyll ‘ at the junction of the leaf base and the upturned lamina ’ in both S. rupestris and 
S. Lyallii; she regards the ‘ strongly recurved portion ’ in these two species as a special protective 
adaptation, but does not add any description- 
N n 2 
