382 
DR JOHN M‘LEAN THOMPSON ON THE 
pinnas are extra-marginal, though the leaf-trace has become much simplified 
(text-fig. 21 (<*)-(/)). But to the more distal pinnae a marginal supply is provided 
(text-fig. 22 (a)-(c)). 
The divided leaf-trace and the dominant extra-marginal pinna-trace supply in the 
Text-fig. 17 . 
robust portions of the leaf constitute advanced features, and the undivided trace 
and marginal pinna-trace supply in the distal parts are the natural accompaniments 
of vascular reduction. 
The vascular condition of this plant may be better understood by comparison 
with an advanced Gymnogramme type. For this purpose Gymnogramme japonica, 
Desv., may reasonably be employed. A reconstruction of part of its stele is shown 
in fig. 56, and a series of diagrams of transverse sections of its stem constitute 
text-fig. 23. From these it will be seen that the vascular system is a perforated 
dictyostele. The perforations are confined to the robust portion, and affect both the 
