Stems Foliage Cones 
Calamites Suckowii Annularia stellata =Macrostachya Thompsonii 
C. carinatus A, radiata Calamostachys Solmsii 
C. ramosus A. sphenophylloides C. magna 
Asterophyllites equisetiformis C. germanica 
Palaeostachya sp. 
‘ 
In other words, there are three ‘‘species’’ of stems, 
four of foliage, and five of cones. The various “‘generic’”’ 
designations indicated above are form-genera. In the 
study of fossil plants, the paleobotanist has to contend 
with fragmentary and detached specimens. Hence a cone 
will receive generic and specific names, as will a stem and 
a leat-whorl. Ultimately the discovery of a more com- 
plete specimen may bring together these various parts 
under one “biological species.’’ This may seem confus- 
ing, but in practice it has been useful and simple. The 
foliage of Macrostachya Thompsonu is an Annularia, 
because the Asterophyllites leaves from Mazon Creek be- 
long to a Calamostachys, probably C. magna. The second 
specimen of Macrostachya Thompsonii (number 15608) 
is accompanied in organic attachment with a poorly pre- 
served, slightly modified, Annularia—probably Jong- 
man’s Annularia stellata americana.” 
The species here named Macrostachya Thompsonii is 
known only from the environs of Mazon Creek in Will 
and Grundy Counties, Illinois. It is distinct from other 
Macrostochya cones collected at Cannelton, Beaver 
County, Pennsylvania. The geologic age of these forms 
is Upper Carboniferous, Allegheny Series, Kittanning 
formation. 
I wish to acknowledge my gratitude to Lady Isabel 
Browne, Professor Walter Gothan, and Professor W.J. 
Jongmans for their generosity in presenting to me va- 
rious publications relating to this study. 
18 7 
Jongmans and Gothan: Geol. Bur. Heerlen Jaarverslag 1933, p.36. 
[ 63 ] 
