The occurrence of fossil plants in the form of isolated fragments is a constant source of difficulty, and is well illustrated by the numerous examples of strobili which cannot be connected with their parent stems. We are, however, usually able to recognise Calamitean cones if the impressions or petrified specimens are fairly well preserved, but it is seldom possible to correlate particular types of cones with the corresponding species of foliage-shoots or stems. Palaeobotanical literature contains numerous illustrations and descriptions of long and narrow strobili designated by different generic terms such as _Volkmannia_, _Brukmannia_, _Calamostachys_, _Macrostachya_ and others; many of these have since been recognised as the cones of _Calamites_, while some species of _Volkmannia_ have been identified with _Sphenophyllum_ stems. Before further considering the general question of Calamite cones, a few examples may be described in detail as types of fructification which are known to have been borne by _Calamites_. The examples selected are species of the two provisional genera _Calamostachys_ and _Palaeostachya_. The usual form of a Calamite cone is illustrated in fig. 93, which represents a fertile shoot bearing a few narrow linear leaves of the _Calamocladus_ type; in the axils of some of these are borne the long strobili. [Illustration: FIG. 93. _Calamostachys_ sp. A fertile Calamitean shoot. From a specimen in the Geological Survey Museum, Jermyn Street, London. From the Upper Coal-Measures of Monmouthshire (No. 5539).] _Calamostachys Binneyana_ (Carr.). Figs. 94 and 95. In 1867 Carruthers[702] gave an account of the structural features of the species of cones named by him _Volkmannia Ludwigi_ and _V. Binneyi_, the generic term having been originally used by Sternberg[703] for some impressions of Carboniferous strobili. Brongniart[704] in 1849 referred to the various forms of _Volkmannia_ as cones of Asterophyllitean branches, and the latter he regarded as the foliage-shoots of a Calamite stem. In 1868 Binney[705] published a description, with several illustrations, of the cones named by Carruthers _Volkmannia Binneyi_, and referred to them as the fructification of that type of Calamite stem spoken of in a previous section of this chapter (p. 311) as _Calamites_ (_Arthropitys_) _communis_ (Binney). This cone is now usually spoken of as _Calamostachys Binneyana_; the specific name _Binneyana_ being suggested by Schimper[706] in 1869 as more euphonious than that proposed by Carruthers. In recent years our knowledge of both _C. Binneyana_ and _C. Ludwigi_ has been considerably extended. We shall confine our attention in the following account to the former species[707]. Some excellent figures of the latter species may be found in Weiss’ Memoir[708] on Calamarieae.