cash: fossil fructificatio:j?s of YORKSHIRE coal measures. 447 
cell body equally is no proof, taking it as I do, in spite of Strasburger's 
recent explanation, as a rudimentary prothallium. As we know, the 
microspores have such a prothallium as well, its more or less strong 
development is not to be considered, and after all, what is Renault 
going to do with Williamson's fruit-spike, containing macrospores 
and microspores. It will have to remain, of course, amongst the 
Annularioe in spite of its resemblance to Calomostachijs Binneyana. 
The only criticism that remains is the secondary wood of the spike, 
and thus we arrive again at the so often mentioned petitio principi 
of Brogniart's school, which makes so difficult to understand the 
writings referred to." 
Though CaJamostachys cannot be regarded as the fruit of 
Calaniites, nor as a very near ally of our Equisetum, yet in the 
present state of our knowledge of fossil botany we may at least 
provisionally include, as Weiss has done, the fruit-spikes we have 
enumerated in one gToup, the Calamarioe. The only living genus of 
the group is the IJqia'sefum, and the following table may serve to 
exhibit the chief points of resemblance and difference between that 
genus and Calamostachys: — 
Fruit-Spikes. 
(The letters given in the tir^t column have each the same import 
in all the figures). 
Equisetum. Calamostachys. 
(Plate 28.) (Plates 22.— 27.) 
Axis - - hollow or fistular - solid 
Sterile Brads - none - - / twelve or more, double 
' the number of the 
( fertile bracts and ar- 
1 ranged in alternate ver- 
ticils with them. 
Sporangiophores stalked peltate discs, /stalked peltate discs, 
(fertile bracts) ^arranged in verticils arranged in verticils, 
/ and in number 6 or 
more, always half as 
many as the sterile 
^ bracts. 
