THE ANATOMY AND AFEINITY OF STROMATOPTERIS MONILIFORMIS, METT. 155 
and is typical of the Gleicheniaceee ; and as such numbers as have been observed 
are uncommon outside Eusporangiate ferns, they form the strongest argument 
which can be advanced in support of an affinity with Gleichenia. The spores are 
peculiar in possessing exceedingly delicate and smooth walls, and may be adapted 
to s conditions of quick germination. 
It is believed that the general characters revealed in this study of Stromatopteris 
justify its recognition as a distinct monotypic genus, allied to Gleichenia , but clearly 
distinguished from it by well-marked peculiarities of form and construction. The 
erect position of the branched portion of the axis of Stromatopteris may be a 
secondary feature, but the recorded facts are wholly insufficient to allow of a 
confident opinion. It has still to be shown whether the horizontal or the vertical 
position was primitive for the axis of Gleichenia itself. The stele of Stromatopteris 
is at points strongly reminiscent of that of Rachiopteris cylindrica, Will. (“A Con- 
tribution to our Knowledge of Rachiopteris cylindrica , Will.,” N. Bancroft, Ann. 
Bot., vol. xxix, 1915), and may prove to be of as primitive a type. The stelar 
structure is not, then, considered a reduction form related to the xerophytic condi- 
tions which appear to have modified Stromatopteris in other respects ; it is rather to 
be considered primitively protostelic. 
DESCRIPTION OF FIGURES IN THE TEXT. 
Text-fig. 1. Axis of Stromatopteris as figured by Mettenius. x f. 
Text-figs. 2-13. Illustrations of the dermal appendages and emergences of Stromatopteris. These 
range from simple hairs to irregular and branched scales, and lanceolate scales on massive conical emergences. 
All x 18. 
Text-figs. 14 and 15. Longitudinal and transverse sections of the cortical tissues -of Stromatopteris. 
x 45. 
Text-fig. 16. An arrested leaf of Stromatopteris on the specimen in Edinburgh Herbarium. x §. 
Text-fig. 17. Plan of pinnation and venation in sterile leaf of Stromatopteris. x 8. 
Text-fig. 18. Plan of pinnation, venation, and soral form and position in Stromatopteris. x 8. 
Text-fig. 19. Types of hairs and scales on the receptacle of Stromatopteris. x 35. 
DESCRIPTION OF FIGURES IN THE PLATES. 
Plate I. 
The sections depicted in this plate all belong to specimen represented in fig. 20. 
Figs. 1 and 2. Transverse sections of stele of plant of Stromatopteris , showing steps of first branching, 
x 30. 
Figs. 3 and 4. Sections showing steps of second branching, x 30. 
Figs. 5 and 6. Sections showing steps of branching in right-hand branch during formation of short 
aborted axis and erect petiole. x 30. 
Figs. 7 and 8. Steps of stelar reduction in the arrested axis which is displaced by the above-mentioned 
petiole, x 30. 
