opinion is practically limited to O.g@uthieri. 1t does not 
follow that the case for or against the existence of the 
Paleozoic Gleicheniaceae rests on this point. 
Synangia do occur occasionally in the living genus 
Gleichenia. In other words, the teratological occurrence 
of a biseriate annulus and a synangial condition of the 
sorus in Gleichenia admit the possibility and propriety of 
including Oligocarpia in the Gleicheniaceae. 
The sorus of Oligocarpia may be compared with sev- 
eral types of fructifications attributed to marattiaceous 
ferns. A case in point is Asterotheca notably Asterotheca 
miltoni ( Artis). Asterotheca belongs to the Carboniferous 
eusporangiate complex which can be referred to the Mar- 
attiaceae or toa closely allied family. ‘This similarity may 
indicate phylogenetical relationship. Bower has suggest- 
ed that the type of sorus in Gleichenia is essentially like 
that of the Marattiaceae—that is, derived from it. 
Thus there are two relationships of the sorus which 
are in doubt. If Kidston is correct in regarding the sorus 
to be an annulate synangium, then we observe a type of 
fructification which, as far as | am aware, is not normally 
found in any existing ferns. On the other hand, if there 
are species of the genus which have a uniseriate annulus 
and in which the sporangia are free, then there is no rea- 
son for excluding Oligecarpia from the Gleicheniaceae. 
The Gleicheniaceae are a decadent group which rep- 
resent but a small remnant of a former diverse stock. It 
is to be expected that the earlier members of the group 
fail to conform to the narrow limits of the residual stock 
which has lost much of its plasticity. 
Nevertheless among the comparatively few existing 
members of the family we encounter several remarkable 
characters of variability. ‘The sori of the Gleicheniaceae 
are superficial and are borne in a single row on both sides 
of the midrib. The number of sporangia in a sorus varies 
[ 153 | 
