HICK : SOME RECENT ADVANCES IN BRITISH PALEOBOTANY. 49 
said that the Calamitean affinities of the spike are generally acknow- 
ledged. 
In addition to Calamostachys, there is another type of spike 
which from its structure Williamson long ago described as the " true 
fruit of Calamites"'^- and which he and Scott have further investigated 
in the memoir referred to. They are so convinced of the Calamitean 
nature of this spike that they distinguishitas Calamites pedunculatus, 
but they point out that it bears a close resemblance to the strobilus 
described by Renault under the name of Volkmannia gracilis,^ and 
placed by Solms-Laubach in Weiss's genus Palceostachya.X 
Discussing the question as to whether or not the two types of 
spike have belonged to closely allied plants, they appear to favour 
the view that they have, a view which in the present state of our 
knowledge appears to be the most probable one. Personally I am the 
more inclined to accept it because my own observations have led me 
to the conclusion, that as at present constituted, the genus Calamites 
is a collective one, and includes several forms that may ultimately be 
separated as distinct genera. In that case, it may well be that 
different sections of the group may have had somewhat different 
fruit-spikes. 
Sphenophyllum. 
It has been mentioned above that the fossils, originally described 
by Williamson under the name of Astei'ophyllites.W were subse- 
quently transferred by him to the genus Sphenophyllum.^ This is an 
important change, as it gives the fossils a more definite place among 
Carboniferous Cryptogams, and removes the source of some confusion, 
continental palaeobotanists usually giving the name Asterophyll-ites to 
leafy branches of Calamites or of Calamitean affinities. 
A still more important matter in connection with this genus is 
the discovery recently made by M. Zeiller with respect to its fruit. 
So far back as 1871 Williamson described a fossil fruit-spike under 
*Phil. Trans., 1888. 
t Annales des Sciences Naturelles, Botanique, series 4, tome iii. 
X Fossil Botany, p. 332. 
II Phil. Trans., 1874, 1878. 
§ General, Morphological and Histological Index, part ii. 
