I 10 
Lady Isabel Browne. 
mality is not exactly rare in Equisetum, and that the figure he 
gives of it shows very clearly the close relationship of Equisetum 
and Phyllotheca ; he characterises the phenomenon represented by 
this spike of Equisetum as probably atavistic (10). Mr. Seward 
mentions the resemblance pointed out by Potonie between Phyllo¬ 
theca and such an Equisetum and remarks that it suggests a partial 
reversion to a Calamitean type (16). From this it would seem that 
these authors incline to the view that the strobilus of Equisetum 
arose from a Calamitean type of cone ; but they offer no explanation 
of the absence ot fertility of the Calamitean bracts. The present 
writer is not inclined to attach much importance to an abnormality; 
it seems more probable that the ancestors of the recent Equisetum 
and the mesozoic Equisetites had cones of the Archaeocalamitean 
type ; it is true that the latter genus is a very ancient one, but a 
somewhat similar type of strobilus seems to have characterized 
the Permian AutophyHites, and whether Equisetites Hemingwayi be 
rightly named or not it proves the existence of an Equisetum- like 
strobilus in the Carboniferous age, and may prove to be on or near 
the direct line of descent of the Equisetacese. 
The strobilus of Cingularia remains to be discussed. In the 
absence of structural specimens Professor Lignier, who upholds the 
view that the sporangiophores of. Calamostachys are the displaced 
ventral segments of the sporophylls, has suggested that in Cingularia 
this displacement has been carried further, and that the sporangio¬ 
phores are the ventral segments of the sterile whorl below them 
and do not belong to the whorl to which they are approximated (8). 
Dr. Scott has recently stated that this may be so (15). Butin view 
of the fact that in Sphenophyllum fertile both lobes of the sporophyll 
are fertile and that in the very ancient Archaeocalamites all the 
appendages of the cone appear to be fertile, it seems more probable 
that the sporangiophores of Cingularia are the dorsal lobes of 
dorsiventrally lobed sporophylls, both lobes of which were presumably 
originally fertile, and that the ventral lobes of these sporophylls 
have been sterilized. This is borne out by Dr. Scott’s statement 
that, according to the latest observations, the sporangiophores 
appear to have been partially fused with the whorl of bracts above 
them, which would be improbable if they belonged to the whorl 
below (15). Professor Lignier sought on general anatomical grounds 
to harmonize the structure of the cone in Cingularia and the 
Sphenophyllales, and as Sphenophyllum fertile was at that time 
unknown he was obliged to regard the fertile members as ventral 
