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DE JOHN M‘LEAN THOMPSON ON 
range from irregularly inserted hairs to massive domes and tortuous and branched 
scales. They are open to interpretation either as excretory structures or organs of 
absorption. Support for this latter view of these appendages is found in the fact that 
no roots have been observed in Stromatopteris, and Mettenitjs has clearly affirmed 
that they are entirely absent. A belief in the specialisation of these appendages 
as organs of absorption is further strengthened by the structure of the cortex of the 
stem, which is composed of thick-walled and elaborately pitted elements, devoid of 
protoplasts and intercellular spaces. These cortical cells may possibly form a supple- 
mentary conductive system. In external form Stromatopteris holds a unique position 
among the Gleicheniacese, and its aloofness is further accentuated by its apparently 
rootless condition, and by its possession of dermal appendages of anomalous type. 
But, on the other hand, it resembles certain of the Gleichenias in possessing conical 
sclerotic emergences which act as supports for certain of the dermal appendages. 
Such emergences are uncommon among ferns, and their possession by Stromatopteris 
tends to strengthen its affinity with Gleichenia. 
The protostelic axis of Stromatopteris is in accord with that of most Gleicheni- 
aceous plants, and any peculiarities which are associated with the branching of the 
stele are believed to be the result of abortion. The leaf-trace is of an advanced 
Gleicheniaceous type, but when arrest and abortion of the leaf-bearing axis have been 
accompanied by dominance of the leaf, and when the latter appears as a distinct 
upward continuation of the axis, the passage from the protostele of the axis to the 
typical foliar trace is gradual. Abortion within the leaf itself leads to abnormal 
structure, which cannot be safely cited in a phyletic discussion. 
The characters of the pinnate portion of the leaf are such as to strengthen the 
relationship between Stromatopteris and Gleichenia. The small orbicular pinnae have 
sympodial dichotomous venation, and the pinna-trace supply is extra-marginal. 
The pinnae are of a leathery character, and their construction is indicative of 
specialisation for a xerophytic existence. 
The sori are developed singly upon the forking of a basal acroscopic vein. The 
receptacle is massive, and either disc-shaped or reniform. Its surface is clothed by 
a curious assemblage of branched hairs and small scales, and it bears a variable 
number of short and massive-stalked sporangia. The position of the sorus, the form 
of the receptacle, and the variation in sporangial number are in keeping with the 
characters of certain Gleichenias , especially of the section Eugleichenia. 
The apparently typical sporangium has a short and massive stalk, a globular head, 
a transverse or oblique annulus, and vertical dehiscence. In form and dehiscence 
the sporangia of Stromatopteris are typically Gleicheniaceous, but anomalies of form 
occur. These affect in particular the size of the sporangium and the form of the 
annulus, but do not appear greatly to disturb the spore-output. Their presence is 
held to indicate a certain aloofness on the part of Stromatopteris from Gleichenia , 
rather than to indicate for the former some other affinity. The spore-output is high 
