Bower . — Studies in the Phytogeny of the Fili cales. 299 
In this respect it shows a marked difference from other Cyatheaceae, in 
which the stomium shows a high degree of differentiation. In point of size 
also, and in the number of tabular cells forming its lateral walls, the 
sporangium of Lophosorici corresponds rather to the Gleicheniaceae than to 
the Cyatheaceae. But in the spore-output it is otherwise. The number 
per sporangium in the Gleicheniaceae is large. In Lophosoria it is only 64, 
a number which tallies with that of Alsophila and Cyathea medullaris , 
though that in C. de alb at a is much lower. Taking all these soral characters 
together it seems clear that Lophosoria holds a very interesting middle 
position between the Gleicheniaceae and Cyatheaceae, and the characters 
are such as accord with the view that its sorus and sporangium were 
originally of the Gleicheniaceous type ; but that while the plant has 
retained the sorus of the Simplices, it has parted with the primitive mode 
of dehiscence, and the originally large spore output of the individual 
sporangium is here represented on a greatly reduced scale. 
7. The details of the prothallus and sexual organs of Lophosoria being- 
still deficient, comparison on these points must be deferred. 
Other Genera of Ferns with Superficial Sori and 
Basal Indusium. 
There are a number of genera of Ferns, containing each relatively few 
species, individually of moderate or small size, which share with the 
Cyatheaceae the possession of a superficial sorus with a basal indusium ; 
some of these prove even to have also like them a basipetal sequence of 
origin of their sporangia upon the receptacle. They have been ranked by 
various systematists as related to the Cyatheaceae, and they are placed by 
Diels immediately after them (Engler u. Prantl, ‘ Nat. Pflanzenfam.,’ i. 4, 
p. 159). They are as follows: Struthiopteris and Onoclea, Peranema and 
Diacalpe , Woodsia and Hypoderris , Cy stop ter is and Acrophorus . Their 
characters show that these genera are naturally grouped together in pairs, 
as above, each of these being more nearly related to one another 
than the pairs themselves are inter se. In order to arrive at some con- 
clusion as to the phyletic relations of these pairs of genera to the Cyathe- 
aceae, and to one another, comparisons must be instituted so far as possible 
on the basis of those criteria which have been employed above. None of 
these Ferns, however, are essentially primitive types. This is indicated by 
the fact that they all show a more or less advanced state of dictyostely in 
the stock, in some cases with the peculiar basket-like structure owing to 
deep involutions of the superficial tissues. Their leaf-trace is divided, but 
not usually in an advanced degree. The venation is in most cases open, 
but in Onoclea and Hypoderris it is reticulate. Broad scales are common, 
in place of or in addition to the more primitive hairs. Some of them have 
a mixed sorus, while the sporangia usually have the annulus interrupted at 
