Sykes and Stiles .— The Cones of the Genus Selaginella. 529 
there are a few cells with feebly lignified walls in the stalk of the sporangium, 
but they are not arranged in rows stretching across it. In 5 . Vogelii the 
sporangium has an unusually long stalk. 
*S. apus, var. elegans , probably also belongs to this group. In the young 
cone the sporophyll enfolds the sporangium as in other species of this 
type ; the tip of the sporophyll is also turned inwards over the young 
sporangium in order the better to protect it. The mature microsporangium 
projects from the enclosing sporophyll, and the association of the mature 
megasporangium with the sporophyll is not at all close ; indeed, in many 
cases it is even difficult to be sure which leaf is the one by which the 
megasporangium was enfolded when young. 
As in vS. Vogelii, the sporophyll has no dorsal projection at its base. 
A narrow longitudinal ridge {in, Fig. 13 e), occupied by an air cavity, is 
however present on the dorsal surface, beginning a little above the base and 
running, at the back of the midrib, nearly up to the tip of the sporophyll. 1 
This dorsal ridge with its air cavity crossed by trabeculae is very characteris¬ 
tically seen in the V-shaped transverse sections of the microsporophyll. 
The distribution of the two kinds of sporangia is a feature of some 
interest in this species. In the plants grown in the Botanic Garden micro¬ 
sporangia were rare, and at least one plant occurred on which megasporangia 
only were found, while in another plant there was only one mature micro- 
sporangium, but numerous megasporangia ; in all cases the megasporangia 
were largely in excess. A single megasporangium is generally borne at the 
base of a terminal cone, which otherwise consists only of a tuft of leaves each 
associated with an abortive sporangium. In a few cases one or two mature 
microsporangia occurred in the same tuft as the megasporangium. Abor¬ 
tive sporangia were frequent in all cases, and one cone consisted of aborted 
sporangia only. 2 At first it was thought possible that the mega- and micro- 
sporangia in this species might ripen at different times on the same plant, 
but it was found that in a short time the few microsporangia had dehisced ; 
at the end of two months all the megaspores had fallen, and there was no 
sign of further development of microsporangia. 3 
The number of megaspores in the megasporangium is extremely 
variable ; 4 in several cases the sporangium contained a single large fertile 
1 It appears probable that the small ridge here described is comparable with the median longi¬ 
tudinal wing recorded by Goebel in some of the sporophylls of species whose cones are dorsiventral 
(Goebel, K., 1901, p. 225 ; and Organography, ii, p. 508, Fig. 340 ( S. sttberosa)). 
2 It is unnecessary to append figures of these abortive microsporangia, as exactly similar ones have 
been figured by Miss Mitchell in S. Kraussiana (1910, Fig. 12, PI. IV). 
3 Lyon, F., 1901, p. 183, refers to the limited number of microsporangia in her material of S. apus. 
It is interesting to find that in S. rupeslris also, the other form recorded as exhibiting reduction in 
the number of megaspores in the megasporangium, Hieronymus remarks that he was unable to find 
any microsporangia ; he tentatively suggests that the embryos in this form may be parthenogenetic. 
It is hoped to investigate the problem later in S. apus. 
4 Cf. Lyon, F. (1901). In S. apus she found four megaspores, but in S. rupeslris she found 
a varying number. 
