Helen N. Armour. 
its original function even here. More evidence is however required 
on this point. 
In the simpler polycyclic forms of solenostely, the internal 
strands are not directly connected with roots, and must be regarded 
simply as water reservoirs, filled and emptied through the nodal 
connexion. The internal system reaches its highest degree of 
efficiency only in dissected types like Angiopteris, in which the 
internal systems have a direct supply of their own from independent 
roots. 
ON THE SORUS OF DIPTERIS, 
By Helen M. Armour, M.A., B.Sc., 
Robert Donaldson Scholar, Glasgow University. 
[Figs. 11—14.] 
1ROM time to time since 1823 the external characters of the 
genus Dipteris have been described, and its division into 
four species has been established. Its systematic position has also 
been discussed by various authors, such as Brown, the earliest of 
these, Moore and Hooker, and later by Christ and Diels. But the 
latest and most detailed description of the family is contained in 
the account published by Mr. Seward and Miss Dale in 1901 of 
“The Structure and Affinities of Dipteris, with Notes on the 
Geological History of the Dipteridineae.” This paper is based 
mainly on a study of Dipteris conjngata, of which material was- 
obtained both from Borneo and the Malay Peninsula. Most 
attention is devoted to the anatomical structure of this one species 
of the family, but the detailed account is prefaced by a general 
survey of the whole group, which embodies the results of the 
earlier workers. The appearance of each species is noted, and then 
it is stated that “ the sori which are without an indusium, consist 
of numerous sporangia and filamentous paraphyses terminating in 
