were borne in separate cones. However, there is no evi- 
dence to support this possibility. 
It will be observed that in many respects Macro- 
stachya Thompsoni resembles the better-known genus 
Calamostachys. At the same time the gross appearance 
of the cone is very unlike the smaller, lax, not imbricated 
Calamostachys. 
Huttonia spicata Sternberg" is in general form simi- 
lar to Macrostachya. In its structure, however, it appears 
to be a typical Palaeostachya’. The resemblance of Mac- 
rostachya to structural plans known under other generic 
names, may indicate that Macrostachya is an unnatural 
group of large cones of which no structure is known. In 
this case, as soon as internal anatomy is known, the sev- 
eral species would be transferred to either Calamostachys 
or Palaeostachya. This is probably an extreme view 
which cannot be defended. 
In the recent discussions of the phylogeny of the 
sphenopsids or articulates (Browne", Zimmerman") no 
mention is made of Macrostachya. It will be seen from 
the foregoing account that Macrostachya in no way al- 
ters the conventional interpretations concerning the cal- 
amarian cone. 
At this time it is not possible to determine the parent- 
plant of Macrostachya Thompsonii. Among the Mazon 
Creek plants there are many detached parts of Calamites. 
All of the calamarian cones (Macrostachya, Calamo- 
stachys, Palaeostachya, Cingularia) are borne by Cala- 
mites. The following ‘species’? are known from the 
Mazon Creek flora: 
“ Hirmer: Handbuch, p. 455. 1927, 
 Jongmans : Anleitung Bestimmung Karbonpflanzen, p.354. 1911, 
Browne: Ann. Bot., v. 41. p. 301-320. 1926, 
'’ Zimmermann : Phylogenie der Pflanzen, 1930. 
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