620 FILICALES 
types of leaf, to which that of Dipzeris is related by D. Lobdiana; but 
from this simple narrow-leaved type, with its single row of sori on either 
side of the midrib, the broader-leaved Dipéeris has broken away as its leaf- 
area enlarged, and the sori have been spread over the extended surface, 
while the absence of their individuality gives the key to the way in which 
Fic. 344. Fic. 345. 
* + 
Dipteris Lobbiana (Hook.), Moore. From a specimen collected by Capt. Hope, R.N., 
Parts of two pinnae, showing narrow form, on the ‘‘China Station,” but without exact locality: 
venation, and regular disposition of the recognised as Difteris guinguefurcata, Baker. Pinna 
showing greater width, and sori arranged below in two 
lateral series as in D. Lobbiana, but spreading out 
upwards, with many fissions, over the more extended 
surface. Natural size. 
sori. Natural size. 
the result has been brought about, viz. by fission. This process, so clearly 
seen in the few species of this very natural genus, has probably occurred 
also in other types of Ferns. It is suggested by Kawlfussta among the 
Marattiaceae, but much more obviously in various lines of the Polypodiaceae. 
It will have to be reckoned with in any general conception of the phylogeny 
of the leaf in Ferns. 
Examining the sorus itself, it is composed of a number of sporangia, 
and numerous glandular hairs are associated with them. The sporangia 
