An exceedingly common Calamitean cast, _C. Suckowi_ Brongn. (fig. 82) affords a good illustration of this type of stem. In the specimen shown in fig. 82 we have a cast of a rhizome, which is rather exceptional in showing three branches in connection with one another. The appearance of the fossil suggests a rhizome, rather than an aerial shoot, bearing lateral branches; the narrowing of the branches and the rapid decrease in the length of the internodes towards the point of attachment being features associated with rhizomes rather than with aerial branches. _Calamites_ (_Stylocalamites_) _Suckowi_, Brongn. Fig. 82. 1818. _Phytolithus sulcatus_, Steinhauer[802]. 1825. _Calamites decoratus_, Artis[803]. 1828. _Calamites Suckowi_, Brongniart[804]. 1833. _Calamites cannaeformis_, Lindley and Hutton[805]. For more complete lists of synonyms of this species reference should be made to Kidston[806], Zeiller[807], and other authors. Casts of _Calamites Suckowi_ are characterised by flat or slightly convex internodal ridges separated by shallow depressions, the ridges are rounded at the upper end of each internode, and usually bear circular casts of infranodal canals. There are some unusually large examples of casts of this species in the British Museum from the Radstock Coal-Measures; one of these has a length of 81 cm., and a diameter of 27 cm. Specimens are not infrequently found with verticils of slender roots in close proximity to the nodes of the cast; figures of such root-bearing casts have been given by Lindley and Hutton[808], Weiss[809], and other authors. Renault[810] has drawn attention to the thinness of the layer of wood which is often associated with large casts of _C. Suckowi_; he concludes that the stems must have possessed little or no secondary wood. In a more recent work by Grand’Eury[811] _Calamites Suckowi_ is spoken of as having had wood of the _Calamodendron_ type, but as wood of this kind has not been found in England, it is suggested that the plant may not have assumed an arborescent habit until late in the Coal-Measure period. During the Lower and Middle Coal-Measures, at which horizon it commonly occurs in England, it may have been herbaceous. This suggestion has little to commend it; the close agreement between _C. Suckowi_ from English and French localities points to a plant of the same form, and we have no satisfactory evidence as to any difference in stem-structure in the two cases. Stur has figured a specimen of a Calamite cast, which he compares with _C. Suckowi_, surrounded by a band of silicified wood apparently of the _Arthropitys_ type. From this and other facts it would appear probable that some of the English stems with the _Arthropitys_ structure possessed casts referable to _Calamites_ (_Stylocalamites_) _Suckowi_.