352 ON THE STRUCTURE OF THE FRUIT OF CALAMITES. 
lines more or less separated from the spores. These I believe to be 
elaters similar in structure to those of Equisetam. In the unripe 
spores they remain coiled up within the original delicate mother-cell ; 
but when the spore has arrived at maturity, and the hygrometric con- 
ditions are present, the spiral bands burst the cell, and spread from the 
spore, as seen in Fig. 1. 
The relation that this strobilus bears to the ordinary foliage of 
Calamites is obvious. The whorled leaves described under the name 
of Aster ophyllites have been frequently found joined to stems of Cala- 
mites, putting beyond all doubt that they are the foliage of at least 
some species of this genus. The branches are in verticils around the 
stem, and the leaves are similarly arranged on the branches. The 
different species are distinguished by the number and form of the 
leaves. The strobilus is simply a shortened branch, with the leaves of 
one series of whorls developed into fruit-bearing organs, while the 
leaves of the alternating series are slightly modified to protect the spo- 
rangia. The arrangement of the strobili on the supporting branches 
also exactlv agrees with that of the branchlets on the branches, as is 
seen in V. Luchoigl, Meyer's Pakeont. x. tab. 11, fig. 2 ; V. polysta- 
chya, Sternb. Flora d. Vorwelt, i. tab. 41, fig. la; AphylhsUichys 
Jugleriana, Goepp. Journ. of Botany, Vol. V. Tab. LXVIIL, etc. 
The structure of this strobilus is obviously very near to that of the 
recent Equisetacea. Indeed, the only difference between the two is, that 
the strobilus of Equisetum is wholly composed of peltate fruit-bearing 
leaves, while in the fossil these alternate with a series of simple pro- 
a 
tecting leaves. This difference is not sufficient to warrant the esta- 
blishment of a new Order for the fossil forms, especially when it is 
remembered that there are so many other points in which the fruits agree, 
viz. the form of the fruit-bearing leaf; the number and arrangement of 
the sporangia ; the peculiar structure of the wall of the sporangium, 
which, though not identical in the two, is a very nearly allied structure ; 
the form and structure of the spores ; and especially the presence of ela- 
ters attached to the individual spores, — a character known only in. 
Equisetum and Calamites. But, in admitting this fossil form into 
Equisetacerp, the characters of that Order must be somewhat modified. 
Whethe 
l *-> 
than that of the living genus, is a question on which there may be some 
difference of opinion. It seems, however, to nie, reasoning by analog) 
