of the Anatomy of the Genus Selaginella , Spr. 135 
these developmental questions it is not my intention, at least 
in the present paper, to enter ; but rather to confine myself to 
the investigation of the anatomy of the mature plant. I shall 
have occasion in my next paper to refer to the structure of 
the growing apex in connexion with the mode of origin of the 
leaf and ligule. 
In the naming of the species I have followed Baker’s con- 
venient manual (4), with reference also to other well-known 
systematic works, more especially those of Spring (6), Kuhn (9), 
Braun (7, 8), and M c Nab (10). For convenience of anatomical 
comparison, however, I have grouped the species according to 
the number of steles in the erect shoot-axis, although I would 
wish it to be understood that this method of classification 
is for present convenience only, and does not necessarily 
express definite views as to the relationships of the species 
treated of. 
I am greatly indebted to various botanists who have most 
kindly aided me in my work. I am more especially under 
obligation to Professor Dr. Graf zu Solms-Laubach, at whose 
suggestion and in whose laboratory in the University of 
Strassburg the work was first undertaken. I have to thank 
the Director of the Royal Gardens, Kew, for permission to 
carry on my work in the Jodrell Laboratory, and for access 
to the splendid collection of Selaginellas cultivated in the 
gardens. To Professors Farlow, Bower, and Bay ley Balfour, 
and to Dr. King and Mr. Moore, my thanks are also due for 
fresh material from the Botanic Gardens of Harvard, Glasgow, 
Edinburgh, Calcutta, and Dublin respectively. I am further 
indebted to Dr. D. H. Scott, who has been so kind as to give 
me the benefit of his criticisms on several anatomical points. 
Lastly, I must record my acknowledgements to my Demon- 
strator, Mr. A. J. Ewart, B.Sc., for relieving me largely from 
the mechanical labour of imbedding and section-cutting. 
Messrs. Veitch, of Chelsea, have taken pains to supply me 
with much material which I required in duplicate. 
The following list includes all the more important papers 
known to me as treating of the anatomy of the genus, more 
