kidston: the flora of the carboniferous period. 199 
A specimen in the British Museum shows that the cones 
of Eqiiisetites Hemingwayi were apparently sessile and borne at 
the nodes of a very Equisetum-like stem. 
MM. Renault and Zeiller have described from the Comentry 
Coal Field an Equisetaceous stem, with distinct sheatlis, under 
the name of E. Monyi. Some other small specimens from 
the Carboniferous have been ascribed to Equisetites, but their 
reference is in many cases doubtful. 
Calamites Suckow. 
The Calamites form one of the most prominent types of 
vegetation in Coal Measure times. True Calamites do occur in 
Lower Carboniferous rocks, that is, below the Millstone Grit, 
but there they take a very unimportant place and are of very 
rare occurrence. It is only when we reach the Upper Carbon- 
iferous that they attain their importance, both in numbers and 
diversity of form. Calamites reached to arborescent dimensions. 
When dealing with the Calamites, we are under the necessity 
of placing the stems, foliage, and fructification of the plants 
comprised in this group in separate genera, as in few cases 
can the foliage and fruit be referred to the parent plant. In 
fact, even in the genus Calamites in which the stems are placed, 
there are almost certainly included plants which belong to 
different genera. One is led to infer this from the structure 
of Calamitic cones which show among themselves important 
structural differences. This fact must not be lost sight of, and 
the genus Calamites should be regarded more in the light of 
a group than of a true genus, but for practical purposes 
some system of classification, even if provisional, must be 
adopted. 
The late Professor Weiss divided Calamites into three 
groups : — 
L — Calamitina. In Calamitina the branches are borne in 
verticils, but between each verticil there is one or more nodes 
from which no branches are developed. 
II. — EucALAMiTES. The stems placed in this group bear 
branches from every node. 
