47 2 Bower. — Studies in the Phytogeny of the Filicales. 
embody do not lead to a phyletic classification, which should be the end 
ultimately to be aimed at. They represent merely 4 states ’ which may be 
transitional or final in any phyletic sequence. It will be apparent at once 
that the grouping according to the original position of the sorus, since it is 
based upon a very early and a very constant distinction, is phyletically 
of greater value than any grouping based on features less constant and later 
in appearance. And this seems to be the true character of the distinction 
between Simplices, Gradatae, and Mixtae. That they are ‘ states ’ passed 
through in distinct phyletic lines was fully realized when these distinctions 
were first drawn ( £ Phil. Trans.,’ vol. cxcii, p. 123). The three divisions were 
then held to ‘ illustrate three steps in the evolution of the sporophyte in the 
Order ’. Moreover it was clearly stated that ‘ the members of each category 
are not to be taken as necessarily of common descent, but are grouped 
according to common adaptation ’. 
The same may, I think, be said of Professor von Goebel’s recent 
suggestion to recognize two groups of Leptosporangiate Ferns as con- 
stituted from related forms (Archegoniatenstudien, xiv, 4 Flora/ Bd. 105, 
p. 51, 1912). Of the Filices Leptosporangiatae he distinguishes as Group I, 
Sporangiis longicidis (the sporangium opening by a longitudinal slit), the 
Osmundaceae, Schizaeaceae, and the Gleicheniaceae. As Group II, Spor- 
angiis brevicidis (the sporangium opening by an oblique or transverse slit), 
the Cyatheaceae, Hymenophyllaceae, and Polypodiaceae. This distinction 
seems to me to suffer under the same disability as that of the Simplices, 
Gradatae, and Mixtae, in that it also cuts athwart the lines based on 
the earlier and more constant character of soral position ; while in itself it 
is based on a circumstance which can be explained as a concomitant, 
or it might even be held merely as a mechanical consequence of the 
arrangement of the sporangia in the sorus. 
The objection to either of these methods of segregation of Lepto- 
sporangiate Ferns is in essence the same as that which opposes the suggestion 
of Kuhn to classify the Polypodiaceae according to the nature of their 
dermal appendages. But they have the advantage in dealing with parts, 
the sporangia, which are of greater importance than the hairs : and it was 
the hairs which Kuhn took as the foundation of his method (Die Gruppe 
der Chaetopterides unter den Polypodiaceen, ‘Festschrift zu dem Jubilaum 
der K. Realschule zu Berlin,’ 1882). Here again a character which is now 
known to have changed in a number of distinct progressive lines had been 
selected. We now know that the segregation of these lines is founded 
on characters anterior to, and more constant than, the distinction of those 
types of the dermal appendages which he used. 
For the reasons thus stated, I find myself unable to accept Professor 
von Goebel’s suggested partition of the Leptosporangiate Ferns. The 
partition according to the original position of the sorus appears to me 
