Specimens of pith-casts occasionally present the appearance of a curved and rapidly tapered ram’s horn, and the narrow end of such a cast is sometimes found in contact with the node of another cast. This juxtaposition of casts is shown unusually well in fig. 82. In some of the published restorations of _Calamites_ the plant is represented as having thick branches attached to the main stem by little more than a point. Williamson[624] clearly explained this apparently unusual and indeed physically impossible method of branching, by means of sections of petrified stems. The branches seen in fig. 82 are of course pith-casts, and in the living plant the pith of each branch was surrounded by a mass of secondary wood developed from as many primary groups of xylem as there are grooves on the surface of the cast, each of the grooves on an internode corresponding to the projecting edge of a xylem group. At the junction of one branch with another the pith was much narrower and the enclosing wood thicker, so that the tapered ends of the cast merely show the continuity by a narrow union between the pith-cavities of different branches. Most probably the casts of fig. 82 are those of a branched rhizome which grew underground, giving off aerial shoots and adventitious roots. There is a fairly close resemblance between the Calamite casts of fig. 82 and a stout branching rhizome of a Bamboo, _e.g._ _Bambusa arundinacea_ Willd.; it is not surprising that the earlier writers looked upon the Calamite as a reed-like plant.