1907-8.] Morphology of the Cone of Lycopodium cernuum. 367 
portion of the sporophyll-base would destroy the indications of the continuity 
of this with the alternating sporophyll-bases to either side, and, as in 
the mature cone of L. cernuum, this is only to be found in the relations 
of the distal portion of the leaf -base to the alternating sporophylls lower on 
the axis of the cone. The sporangium in Spencerites is inserted on a special 
outgrowth which on this view springs from the upper surface of the distal 
region of the radially extended sporophyll-base. It is, I think, open to 
question whether any special morphological significance should be attached 
to this outgrowth. There does not appear to be any evidence to justify the 
interpretation of the region between the insertion of the sporangium and 
the axis of the cone as being of axial nature either in the recent or the 
extinct plant. This region in L. cernuum is intercalated late in the 
ontogeny, and the same may have been the case in Spencerites. 
Allowing for the smaller size and simpler structure of the cone of 
L. cernuum, the resemblances between it and the cone of Spencerites appear 
to be so close that it is difficult to avoid the conclusion that the plants are 
related. Taking the probability of Spencerites having been eligulate and 
homosporous into consideration, the resemblances appear to point to the 
inclusion of Spencerites and Lycopodium in the same great subdivison of 
the Lycopodiales. There does not appear to be any evidence for deriving 
this eligulate group from Lepidodendron or any other member of the 
ligalate Lycopodiales. To what extent Spencerites is more especially related 
to Lycopodium cernuum itself or presents a similar development, as regards 
the complexity of the cone, from a common type ; to what extent the genus 
Lycopodium is a natural one, and whether the simpler existing forms are 
reduced or simply persistent types, are matters for critical inquiry in the 
light of all the available evidence, not merely that afforded by the morpho- 
logy of the cone. 
I have pleasure in acknowledging the assistance I have received both 
in discussion and in the provision of material from Professor Bower and 
Dr Kidston. To the authorities of the Natural History Department 
of the British Museum I am indebted for facilities in consulting the 
specimens in the Williamson Collection. 
