io Bower. — Studies in the Phytogeny of the Filicales . VI. 
intercalary zone remains thin-walled long after the distal region has become 
mature and indurated. The insertion of the scale upon the rhizome is at 
the base of a funnel-like pit in the surface of the rhizome, two or three cells 
deep. The stalk of the scale fills this, but as it emerges from the pit it 
expands right and left at once, so that the peltate scale is in close relation 
to the surface of the rhizome. 
The interest of these details lies in the comparison on the one hand 
with Dipteris and Cheiropleuria , on the other with Platycerium and some 
other Ferns. Comparing with the Matonia-Dipteris series, the hairs of 
Matonia consist of a single row of cells, with a basal intercalary zone, while 
distally the cells have brown indurated walls, and run out to a pointed tip . 1 
In Dipteris conjugata the smaller hairs may have the same structure ; but 
various stages of increasing complexity are seen, which are initiated by 
longitudinal divisions of the basal cells. This region widens into a 
massive structure with greatly indurated walls . 2 In both of these Ferns the 
hairs are inserted on the ordinary surface of the rhizome. In Leptochilus 
tricuspis the construction is essentially of the same type, but with the addi- 
tion of the peltate expansion at the base and the sessile marginal glands : 
moreover the stalks of the scales are sunk in pits. Thus all of these are 
essentially of the same type, but show successive steps of increasing com- 
plexity. 
Comparing on the other hand with Platycerium , the scales of the 
rhizome there found are of the same type as regards their peltate form and 
the intercalary zone at the base. They vary in size in different species : in 
P. alcicorne they are smaller and narrower. They are, however, inserted 
not in an involution of surface of the rhizome but upon a convex emergence : 
so that the scale is not in such close relation to the surface as in Leptochilus 
tricuspis . This is a state similar to that seen in many Cyatheaceae, where 
the emergences mature into the thorns about the leaf-base. A like condition 
is seen in many species of Gleichenia , at the base of the leaf-stalk . 3 In 
Platycerium the induration is restricted to the central region of the scale, 
but it is heavier than in Leptochilus , and darker in colour. The most 
marked feature of resemblance is in the glands at the margin. Many of the 
marginal cells give rise to a hair, composed of two or more cells, of which 
the last is a gland (Text-fig. 4, c ). It may thus be held that the scales of 
the rhizome of Platycerium correspond in form, development, and glan- 
dular appendages to those of Leptochilus ; but they are more specialized 
in their details, and are borne on projecting emergences instead of being 
sunk in pits. 
For further comparison a drawing is given of the margin of a scale of 
1 Seward: Phil. Trans., B, vol. 191, PI. 19, Fig. 32. 
2 Seward: Phil. Trans., B, vol. 194, PI. 49, Figs. 29, 30, 36. 
3 Ann. of Bot., vol. xxvi, 1912, pp. 272-3. 
