P teridophy tes . Are they vestigial? 255 
the simple and the double-bladed forms ; he remarks, however, 
that where they are more or less deeply cut or completely 
bifurcate there is almost always the rudiment of the synangium, 
initiated but not brought to full development, in the form of 
an outgrowth usually of brownish colour. 
These facts for the Psilotaceae are plainly comparable with 
those in Lycopodium ; and similar arguments might be based 
on them. But the case here cannot be so well appreciated, 
nor such clear conclusions drawn, owing to the fact that the 
group is isolated and represented by few living species ; and 
secondly, that the embryology is not known, while in the 
well-grown plants there is a long basal vegetative region 
before synangia first appear. 
It is thus seen that abortive sporangia are found in all the 
genera of Lycopodineae, and, with the exception of Phyllo- 
glossum , at both the upper and lower limits of the fertile zone ; 
often also within the fertile zone itself. The bearing of these 
facts has been so fully discussed for Lycopodium that no general 
application of them to the other genera need be repeated 
here, for the arguments and conclusions would be virtually 
the same. 
Equisetaceae. 
In other Pteridophyta besides the Lycopodineae abortive 
spore-bearing organs are also found ; for instance in the 
Equisetineae. Bearing in mind the Calamarian strobili, it 
may be an open question whether the annulus at the base 
of the strobilus of Equisetum is really a transitional body 
between the vegetative sheath and the sporangiophores (see 
Scott, Studies in Fossil Botany, p. 61). But whatever view 
be taken on this point, the fact is that frequently smaller 
sporangiophores, with fewer sporangia, or even one only, may 
be found at the base of the strobilus ; this is well seen in 
E. palustre. Sporangia may also be found on the annulus, 
and a good series was figured by Milde \ showing intermediate 
Beitrage z. Kenntniss d. Equiseten (1851), PI. LV, Figs. 21-38. 
