A transverse section of the axis of the cone in the region of the sterile and fertile appendages shows the vascular bundles arranged in pairs. In a section through the peduncle of the cone, below the lowest whorl of bracts, the bundles of the stele are situated at equal distances apart. The cortical tissue of the peduncle is traversed by a ring of large canals[721] similar to the vallecular canals of an Equisetum stem. Isospory is not a constant characteristic of _Palaeostachya_; some forms have been found with macrospores and microspores[722]. _Other Calamitean cones, and examples illustrating the connection between Cones and Vegetative Shoots._ It would be out of place in an introduction to Palaeobotany to attempt an exhaustive account of the various cones which were probably borne by Calamitean plants, but there are a few general points to which the attention of the student should be directed. The examples dealt with in the foregoing description illustrate the fact, that plants included under the comprehensive genus _Calamites_ bore cones possessing distinct morphological features. There are, however, other types of strobili which have been found in organic connection with _Calamites_; and some of these must be taken into account in dealing with Calamarian plants. The genera _Volkmannia_, _Brukmannia_, _Huttonia_, _Macrostachya_, in addition to _Calamostachys_ and _Palaeostachya_ and others, have been applied by different writers to Calamitean cones. As Solms-Laubach[723] has suggested, it is wiser to discard _Volkmannia_ and _Brukmannia_, as they have been made to do duty for cones of widely different forms. It is better to adhere to the provisional generic names used by Weiss, as they enable us to conveniently systematise the various Calamarian strobili. The following classification may be given of the better known cones, some of which we are able to describe in considerable detail, while others are still very imperfectly known. We have good evidence that all these strobili were borne by vegetative shoots of the type of _Calamites_, _Calamocladus_ or _Annularia_. 1. _Calamostachys_[724] (including _Paracalamostachys_ and _Stachannularia_). Cones long and narrow, consisting of a central axis bearing alternate whorls of sterile and fertile appendages, the latter having the form of sporangiophores attached at right angles to the axis midway between the sterile verticils, and bearing four sporangia on the inner face of a peltate distal expansion. _Calamostachys Binneyana_ Schimp., _C. Ludwigi_ Carr., _C. Casheana_ Will., may be referred to as examples of this type of cone; also some of the strobili described by different authors as species of _Volkmannia_[725], _Brukmannia_[726], &c.