ON THE STRUCTURE OF THE FRUIT OF CALAMITES. 355 
There can be no reason, then, for doubting that all these forms 
having a similar arrangement of leaves, and a similar structure of fruit, 
and all moreover abounding in beds where the stems of Calandtes 
occur, belong to the same set of plants. They do not differ more 
from each other than do the foliar appendages of many living genera. 
Even Galium, to which these fossils were referred by Luid, Walch, and 
the early observers, has amongst its species as great a diversity in the 
form of leaf, and almost in the venation, as exists in these fossils : 
Compare G. tier urn, L., G. rubioides, L., G. cordatum, Kcem. and Sch. 
Besides the fruits found associated with the foliage many occur 
isolated which have been referred to separate genera. I have alreadv 
*_. ^ m * * m 
given the names of four such genera, referred by Brongniart to Ade- 
rophjllites, viz. Volkmannia, Bec/cera, Boruia, and Bruc/mamiia, and 
I may add Hutlonia and Aphylhstachys, recently described by Goeppert, 
whose paper and drawing are reproduced in the present volume of the 
'Journal of Botany,' p. 221, and Plate LXVIII. 
The progress made in the elucidation of this singular tribe of plants 
since 1848, when Dr. Hooker published his Essay * On the Vegetation 
of the Carboniferous Period, as compared with that of the present day,' 
the most important contribution towards a correct interpretation of 
the coal plants ever published in the English language,— is very re- 
markable. He says under Calamitea, " I have in vain sought for any 
traces of structure in carefully prepared species of this genus ; or for 
evidence of their being Equisetaee* in the presence of those siliceous 
stomata with which that Order abounds, and which would surely have 
been preserved in the fossil state." We are now able to build up 
the whole plant, and to illustrate even its most minute microscopical 
details. 
Synopsis of EquisetacejE. 
Order Equisetace^:.— Stems herbaceous or arborescent, branched ; 
leaves in whorls ; fruit in terminal or lateral strobili ; sporangia de- 
pendent from peltate leaves ; spores globular, furnished with hygro- 
metric eltiters 
Suborder I. Calamitea .-Stem arborescent or frutescent, woody, 
branched ; leaves in whorls, free or slightly united at their bases ; fruit 
in terminal or lateral strobili composed of alternating series of whorkd 
■liar and fruit-bearing appendages, four sporangia dependent from 
each peltate leaf. 
