Lycopodiales. 165 
prove, on the publication of Mr. Kidston’s description of it, to have 
Lepidodendraceous affinities, it may turn out to be close to the 
direct ancestor of Isoetes. Thus, even if descended from the 
Lepidodendraceas, Isoetes may be primitively non-strobiloid, but, on 
the whole, if we admit the excessive reduction outlined above we 
shall find no difficulty in regarding its non-strobiloid condition as 
due to reduction. 
It will be seen that this question of the origin of Isoetes by 
reduction from the Lepidodendraceac in the widest sense of the 
word is not yet solved, but in the present writer’s opinion there is a 
strong probability that it should be answered in the affirmative. 
LITERATURE QUOTED. 
1. E. A. Newell Arber and H. H. Thomas. “ On the Structure of Sigillaria 
scutellata, Bongn., and other Eusigillarian Stems, in 
comparison with those of other Palaeozoic Lycopods.” 
Proceedings of the Royal Society Series, Vol. 80,1908. 
2. E. M. Berridge. “ On two new specimens of Spcncerites insignis .” 
Annals of Botany, 1905. 
3. F. O. Bower. “ On the Structure of the Axis of Lepidostrobus Browuii, 
Sep.” Annals of Botany, 1893. 
4. ,, “ The Origin of a Land Flora.” 1908. 
5. D. H. Campbell. “ Mosses and Ferns.” Second Edition, 1905. 
6. J. B. Farmer. ‘‘On Isoetes lacustris." Annals of Botany, 1890. 
7. T. G. Hill. “ On the Presence of Parichnos in Recent Plants.” Annals 
of Botany, 1904. 
8. R.Kidston. “ Carboniferous Lycopods and Sphenophylls.” Transactions 
of the Natural History Society of Glasgow, New 
Series, Part I., 1899. 
9. ,, “ On a New Species of Lepidodendron from Pettycur (Lepido- 
dendrun Pettycurense)." Proceedings of the Royal 
Society of Edinburgh, 1906-7, Vol. XXVII. 
10. ,, “ Preliminary Notice on the Internal Structure of Sigillaiia 
mamilUiris , Brongniart, and Sigillaria scutellata, 
Brongniart.” Proceedings of the Royal Society of 
Edinburgh, 1906-7, Vol. XXVII. 
11. A. J. Maslen. “ The Structure of Lepidosti ulus." Transactions of the 
Linnean Society, Scries II., Botany, Vol. V., 1899. 
12. H. Potonie. “ Lehrbuch der Pflanzenpaliiontologie, mit besonderer 
Rucksicht auf die Bediirfnisse des Geologen.” 1899. 
13. D. H. Scott. “ Studies in Fossil Botany,” 1900. 
14. 
» J 
Ditto, Vol. I. 
“ Pteridophyta .” Second edition, 1908. 
