Bower. — Studies in the Phytogeny of the Filicales. VI. 9 
plane across the veins limiting those areolae. It had long been known that 
in the sporophylls of Platycerium a sub-soral vascular system existed. It 
was further shown 1 that if semifertile areas of Platycerium be examined, 
a condition is found more advanced than in Cheiropleuria, and that the 
extension of the soral vascular system, which is seen occasionally in the 
latter, is the rule in Platycerium ; it leads in fully fertile leaves to the sub- 
soral system, which ramifies extensively in a different plane from the 
main reticulum. This is what is now seen also in Leptochilus tricuspis , in 
which it corresponds more nearly to what is seen in Platycerium than in 
the simpler Cheiropleuria^ though it still falls short of the complexity seen in 
the most elaborate examples of the former genus. 
Dermal Appendages. 
The dermal appendages offer features useful for comparison. Both on 
the axis and on the young leaves of Leptochilus tricuspis they are present as 
Text-fig. 4. a — margin of scale of Leptochilus tricuspis ; b — ditto of Neocheiropteris ; 
c = ditto of Platycerium sp, ; d = ditto of Goniophlebium sp. All are magnified 85. 
scales. The largest have a broad shield-like base, with the short stalk of 
attachment intra-marginal, so that the scale is peltate. The scale narrows 
off upwards, and terminates in a very long hair, formed of a single row of 
cells. The terminal cell remains usually thin-walled, but is not enlarged 
as a gland. The greater part of the scale is only one layer of cells in thick- 
ness, but the stalk is more massive. The whole scale is composed of cells 
with thick chestnut-brown walls, but the marginal cells have their marginal 
wall thin. Many of these cells give rise to shortly-stalked glands, which are 
not partitioned by septa from the cells which bear them (Text-fig. 4, a). 
The scale in development originates from a single row of cells, of which 
those of the basal region soon undergo longitudinal division, widening out 
laterally above the short stalk to form the peltate expansion. The enlarged 
region thus formed continues intercalary growth near its base, and the 
1 1 - c., p. 513, Text-figs. 13, 14. 
