478 Sinnott. — Some Jurassic Osmundaceae from Nezv Zealand. 
It expands into a single endarch arch, which in the base of the petiole is 
surrounded by a circular ring of sclerenchyma. On either side of this, in 
the cortex of the stipular wing, is a large island of sclerenchyma, and there 
is a patch of the same tissue inside each lateral bay of the leaf-trace. 
5. The relationship between the Zygopterideae and the Osmundaceae 
cannot be close, since the anatomy of the leaf-trace and foliar bundle in the 
two groups is so widely different. The leaf-trace of the Osmundaceae and 
Ophioglossaceae is typically monarch, whereas that of the Zygopterideae is 
typically diarch. The simple condition of Clepsydropsis probably led rather 
to the diarch and triarch modern Ferns than to the Osmundaceae. 
6. There seem to have been both protostelic and siphonostelic 
Osmundaceae in ancient times, and there is no convincing evidence that 
the protostelic members of the family which we know, such as the genus 
Thamnopteris , have given rise to the species with a pith, for no transitional 
forms have yet been found. Intermediate conditions occur, however, 
between such a primitive siphonostelic type as Osmundites Skidegatensis 
and the most reduced modern species. The xylem elements described as 
forming part of a ‘ mixed pith ’ in Osmundites Kolbei are probably root 
bundles similar to those here described in O. Dunlopi. 
7. The theory of the origin of the Osmundaceae, which assumes that 
they have been reduced from typical siphonostelic forms, has the advantage 
of explaining very many structural facts in living and fossil members of the 
family which remain unaccounted for on any other hypothesis. 
The writer is under much obligation for material to Professor 
P. Marshall, of the University of Otago, New Zealand ; to Mrs. J. Mackintosh, 
of Waikawa, New Zealand ; and to Professor J. H. Faull, of Toronto. 
This work was carried on in the Phanerogamic Laboratories of Harvard 
University under the direction of Professor E. C. Jeffrey, to whom the writer 
is much indebted for information and advice. 
Bibliography. 
1. Kidston, R , and Gwynne-Vaughan, D. T. : On the Fossil Osmundaceae. Parts I-IV. 
Trans. Roy. Soc. Edin., 1907-10. 
2. Faull, J. H. : The Anatomy of the Osmundaceae. Bot. Gaz., vol. xxxii, 1901, pp. 381-419. 
3. Jeffrey, E. C. : The Structure and Development of the Stem in the Pteridophyta and Angio- 
sperms. Phil. Trans. Roy. Soc., B., vol. cxcv, 1902. 
4. Sinnott, E. W. : The Evolution of the Filicinean Leaf-trace. Ann. Bot., vol. xxv, 19H. 
5. Schuster, J. : Osmundites von Sierra Villa Rica in Paraguay. Ber. Deutsch. Bot. Gesell., xxix, 
I9 11 * PP- 534-54°* 
