i'86 JOURNAL, BOMBAY NATURAL HIST. SOCIETl , Vol. XXV. 



imbricated, measuring about 1"7 mm. in length and 1 mm. in breadth (Fio-s. 

 4 & 5). The long axis of each sporophyll is at an angle of about ()0° to 

 that of the stem bearing it (Fig. 3). The sporophyll is clearly oblique ; 

 the half nearest the stem-axis is much bigger than the one away from it, 

 and is besides much more lengthened out, and rounded at the base than 

 the other half (Figs. 4 & o). This stretched out portion partly goes under 

 the stem-axis, and has a depression for lodging the sporangium. The rest 

 of the sporophyll is quite flat and there is no dorsal flap or ridge at all as 

 described by Sykes and Stiles iu the species IS. jrumJla, iS. helvetica, and 

 <S'. caulescen.'i (9). 



The sporophylls of the upper plane are cordate, patent, slightly ciliated 

 and much imbricated (Fig. 6). Each is shortly stalked and measures about 

 1-3 mm. in length and 1 mm. in breadth; thus it is comparatively broader 

 in form than the sporophjdl of the lower plane. Its long axis is at an angle 

 of about 30° to that of the stem (Fig. 3). It is quite flat and symmetrical 

 and there is no dorsal flap or ridge. 



The protection of sporangia is very characteristic in this species. They 

 generally arise in the axils of sporophylls of the lower plane only. Each 

 sporangium is lodged in the depression found iu the stretched out basal 

 part of the sporophyll as mentioned above. The upper surface of the 

 sporangium is covered partly by the stem and partly by a portion of 

 that half of the next higher sporophyll of the upper surface which is away 

 from the axis. This is made possible by the sporophylls of the two planes 

 being inserted at different angles to the stem-axis as noted above. The 

 greater part of the upper sporophyll simply spreads over the stem, while 

 the greater part of the lower ones spreads out free from the stem ; thus the 

 greater part of both kind of sporophylls is easily accessible to light for 

 assimilation. The sporangium is placed between the overlapping por- 

 tions (Fig. 3). In this way each sporangium is, as it were, enclosed, in 

 a chamber formed by the basal parts of the lower and upper sporophylls 

 and a p<»rtion of the stem. This form of sporangium-protection gives 

 another reason why definite sterilizations are taken to be utilitarian. One 

 reason is given by Miss Mitchell who says that these sterilizations ' make 

 for the increased efticiencj^ of the spore production as a whole ' by preserv- 

 ing ' the balance between the spore producing and the vegetative parts ' 

 (8). The additional function of protecting the sporangia can also clearly 

 be attributed to the sterile sporophylls of S. paUidissima. Here the laminas 

 of two sporophylls, both practically flat, take part in the protection of one 

 sporangium. 



General Considerations. 



The chief peculiarities in the cone of S. pril/i<li.tsi)iia can be summed up as 

 its comparatively great size, branched nature, loose insertion of sporo- 

 phylls, very little diS'erence between the sporophylls and the ordinary 

 vegetative leaves in structure and form, indiscriminate distribution of 

 mega — and micro -sporangia, occasional inequality of size in mega-spores, 

 saddle-shaped microaporangia, absence of sporangia from the axils of 

 unper sporophylls, and the peculiar method of protection of sporangia 

 by the sporophylls. The great size, branched nature, and loose in- 

 sertion of sporophylls clearly show that the cone is not much highly 

 advanced towards 'flower' formation. Indiscriminate distribution of 

 mega — and micro-sporangia also tends to show the same according to 

 Mitchell (8). A tranverse section of the stem shows that the species 

 belongs to S. Marten.m group of Harve3'-Gibjon, which is taken as a 

 primitive form of stem structure in the genus SelafpnelUi (6). The steni is 



