44 8 Boiver. — Studies 271 the Phytogeny of the Filicales. 
vertical position, but also by the interruption of the annulus. In form 
the sporangia are slightly flattened. In Fig. 9 I and III represent their 
flattened sides, with the cells of the annulus slightly collapsed on ripening ; 
II and IV show them as seen on edge, and with the cells of the annulus 
fully convex. In Fig. 9, I, the face corresponding to the £ central ’ face 
of the Gleicheniaceous sporangium is shown. The annulus is definitely 
interrupted at the insertion of the stalk, and the cells on either side of the 
stalk are relatively thin-walled. On the side opposite the stomium the full 
induration begins at the third cell, and is continued for sixteen cells. Then 
follow two relatively thin-walled cells ; next come the four cells of the 
stomium, encroaching in this view far over the face of the sporangium ; and 
finally two thinner-walled cells follow, connecting up with the stalk. The 
whole series numbers twenty-seven cells. The tabular cells are in this case 
only seventeen in number. 
Fig. 9, II, represents a similar sporangium seen on edge with the base 
of one of the hairs (h) attached to its stalk. The convexity of its sides 
is seen, while twelve cells of the annulus are visible. Of these the two 
lowest correspond to the two thinner-walled cells in Fig. 9, I. The third 
drawing (Fig. 9, III), which was made from a rather peculiar sporangium, repre- 
sents the opposite face to that shown in Fig. 9, 1, viz. that which corresponds 
to the ‘ peripheral ’ face in Gleichenia. It is, moreover, to be noted that the 
sporangium here represented was the ‘ looking-glass ’ image of that in 
Fig. 9, 1, as regards the side on which the stomium occurs. The fact may be 
stated thus : that in these sporangia as viewed from the peripheral side the 
stomium may be either right or left ; in Fig. 9, I, which is seen from the 
* central’ side, it is right; in Fig. 9, III, which is here seen from the ‘peripheral 5 
face, it is also to the right, which could only happen if they were c looking- 
glass ’ images of one another. The peculiarity of the sporangium seen 
in Fig. 9, III, consists in the annulus being continuous across the insertion of 
the stalk, a condition not unique, but less common than the interrupted 
state ; and the number of the cells of the annulus is here rather larger than 
in the previous case, viz. thirty. The stomium is as before, but it is seen 
that its four cells do not encroach upon the ‘ peripheral ’ face as they did 
upon the ‘ central ’ face of the sporangium in Fig. 9, I. It thus appears 
that the stomium is not laterally symmetrical. The number of tabular cells 
of the ‘ peripheral ’ face is here larger, viz. twenty-five. 
The next drawing, Fig. 9, iv, shows an average sporangium on edge, 
presenting its stomium in surface view. The relation which this bears 
to the annulus and to the c peripheral * face of the sporangium is the same 
as before seen in Fig. 9, I. The ‘ central ’ face, upon which the cells 
of the stomium encroach, is to the left, while the • peripheral ’ is behind and 
to the right, owing to slight obliquity in position of the sporangium. 
Lastly, the stalk shows in Fig. 9, II, four cell-rows, and in Fig. 9, I and IV, 
