Sykes and Stiles .— The Cones of the Genus Selaginella. 527 
projection is much reduced, but is still to some extent adapted to the 
protection of the sporangia below it. Finally, there are sporophylls in 
which this dorsal projection is entirely absent; each sporangium is closely 
enfolded and protected by the sporophyll which subtends it. It would 
seem as if this close enfolding of the sporangium by its own sporophyll 
has gradually taken the place of its protection by outgrowths from other 
sporophylls. 
Type 3. X. Helvetica} The young cone is here composed of compactly 
arranged sporophylls, but in the older cone the internodes become much 
elongated, and the sporophylls no longer overlap (Fig, 6 , a and H, PI. XLI). 
Each sporophyll has a prominent dorsal swelling, which is decurrent; in the 
young cone the two sporangia, which are borne on the alternating sporo¬ 
phylls of the whorl below, are appressed on either side of this swelling 
(Figs. 6 £and 7, PI. XLI). 1 2 In the old cone the sporangia are considerably 
exposed, being only partially protected by the folded edges of the sporophyll 
in the axil of which they are borne. A large air cavity occupies the decurrent 
swollen base of the sporophyll; it extends upwards for a short distance into 
the lamina, being bisected by the entering bundle into two portions ; it is 
crossed by a few trabeculae (Fig. 8, PI. XLI) which increase in number in its 
upper portion. The surface of the sporophyll is provided with a thin cuticle, 
which is less strongly developed in the region covering the swollen base. 
It is obvious from the above description and figures that in this species 
the dorsal projection is of no value for the protection of the sporangium 
except in its youngest stages, and its small size makes it of very little use 
even in the young cone. It may possibly represent the rudimentary remains 
of a well-developed dorsal flap, such as is present in 5 . pmnila , and which 
has here become fused with the stem. 
The macrosporangium in X. Helvetica contains four macrospores. The 
microsporangium is tangentially somewhat elongated, or saddle-shaped. 
An interesting feature is a row of cubical cells with strongly lignified 
but unpitted walls, which stretch across the stalk of the sporangium from 
one epidermis to the other, and are already present even at a stage when the 
sporangium is still quite immature (Figs. 8 and 9, PI. XLI). In some cases 
more than one layer of these peculiar cells may be present. The epidermis 
of the sporangium stalk is also strongly cuticularized. The significance of 
this feature is at present obscure. 
Type 4 a. In X. flabellata and X. caulescens the cone is more compact 
than in the last species, though the sporangia are still to some extent 
visible between the sporophylls. Each sporophyll is here more closely 
1 Hieronymus, G., p. 687, Fig. 405 (no dorsal projection is visible in this figure) ; Luerssen, C., 
Fig. 225, p. 864. 
2 This arrangement is essentially similar to that found in the cone of Lycopodium inundatum , 
though less effective (Sykes, M. G., 1909). 
