278 MR. A. R. HORWOOD ON CALAMITES SCHÜTZEI, AND 
ТА. Description of specimen demonstrating the fistular character of 
the pith in Calamites. 
The specimen from Stanton-under-Bardon is split, 3 inches from the base, 
firstly in a longitudinal direction, and is 3} inches apart at the upper 
extremity. Fourteen inches from the last point the left-hand fork thus 
formed is split again for a length of 12 inches, and at its base is 24 inches from 
the main portion. Split thus in two opposite directions the specimen (a pith- 
cast) affords a graphic demonstration of the fistular character of the pith. 
The fact that pith-casts are filled with mud is in itself a proof of the same 
kind. Originally the now solid centre was hollow. Calamites is more often 
than not, moreover, found as medullary or pith-casts *. Tbe markings on 
their surface merely represent the internal impressions of medullary rays 
and woody wedges seen in some specimens as a thin carbon-crust. In 
young stems, where a pith is found, these casts do not occur, but in old 
specimens these features are represented by the “ridge” and “ furrow” 
of the pith-cast. In these cases, according to Williamson f, the pith has 
been absorbed or resorbed by “а vital process " and not by decay. 
The casts usually found are oval or circular in section, filled with mud, shale, 
etc., flattened or compressed by pressure and other causes. There may or 
may not be an external carbon-crust, due to mode of preservation, character 
of the sediment or waters. Owing to these reasons it is difficult to correlate 
the different form-genera that have been made for fragments of root, stem, 
foliage, and fructification. 
Though the hollow character of the pith has long been known, no clear 
figure has been published to prove this asin the accompanying illustration 
(Plate 18). Lindley and Hutton { figured a crushed example, which “ has 
been struck perpendicularly so as to separate it into many portions.” Their 
figure (3 nat. size) represents a stem split into about ten fragments spread out 
horizontally in a verticillate manner. 
The Stanton-under- Bardon specimen is three inches in width at the base, 
and at the upper extremity the fractured portions together amount to the 
same. 
The specimen now figured throws some light upon a figure of a specimen 
in the ‘Fossil Flora’ referred to Calamites Mougeotii by Lindley and Hutton $. 
What are there regarded as attenuated terminations are simply portions of a 
stem that has been split. 
* An unusually fine specimen showing the pith-cast and woody cylinder of Calamttina 
approximata in Dr. Kidston's collection is figured by Prof. Seward (‘ Fossil Plants,’ vol. i. 
fig. 100). 
T Phil. Trans. Roy. Soc. 1871, p. 494. 
і Fossil Flora, vol. i, pl. 21. 
$ L.c. vol. i., explanation of plate 22, p. 72. 
