Bower. —Studies in the Phytogeny of the Filicales. 521 
also from the side facing one of the rows of segments, instead of taking 
them in profile. Such a view is shown in Fig. 18, b , the appearance of which 
*s consistent with the segmentation by two alternate rows of cleavages. 
Transverse sections also bear out the correctness of the conclusion (Fig. 18,^). 
Miss Armour has already shown (New Phytologist, 1907) that in these sori 
the sporangia are not all of the same age, and Fig. 18, a and c, confirm this. 
Some are found to show only two cells, corresponding to the two rows of 
segments ; others have undergone subdivision of the segments, and show 
as the result the four rows of the mature stalk. 
It is clear from these observations that ‘Dipteris ’ and ‘ Cheiropleuria ’ 
provide a new and distinct type of segmentation of the Fern-Sporangium. 
The similarity which these genera show in other features, when taken to- 
Text-figs. 19, a-g. Segmentation of young sporangium of Metaxya. b are two lateral 
views, at right angles to one another : c } d show the sporangial head in transverse section : c is 
a transverse section of the sporangial stalk; f, a transverse section of an older sporangial head : 
g shows a sporangium of the age of c, d , seen laterally, x 300. 
gether with their similarity in this rare feature, forms a convincing body of 
evidence of their real affinity. 
The only other type of Fern which has been described as having 
constantly four rows of cells of the sporangial stalk is Metaxya (Ann. of 
Bot, xxvii, p. 447, PI. XXXII, Fig. 8). The detail of segmentation of the 
young sporangium, as viewed from above, was not looked into when the 
plant was being investigated ; but it will be seen at once that Figs. 5, 6, on 
the plate quoted, show numerous segmentations, as seen from the side, 
which would accord with a two-sided segmentation. Fresh observations 
were therefore made with the results shown in Text-figs. 19, a-g. The 
drawings a , b show sporangia in which the cap-cell has not yet been 
formed, from points of view at right angles to one another; in the 
Mm2 
