In the earliest works on fossil plants we find several figures of _Calamites_, which are in most cases described as those of fossil reeds or grasses. The _Herbarium diluvianum_ of Scheuchzer[580] contains a figure of a Calamitean cast which is described as probably a reed. Another specimen is figured by Volkmann[581] in his _Silesia subterranea_ and compared with a piece of sugar-cane. A similar flattened cast in the old Woodwardian collection at Cambridge is described by Woodward[582] as “part of a broad long flat leaf, appearing to be of some _Iris_, or rather an Aloe, but ’tis striated without.” Schulze[583], one of the earlier German writers, figured a Calamitean branch bearing verticils of leaves, and described the fossil as probably the impression of an Equisetaceous plant. It has been pointed out by another German writer that the Equisetaceous character of _Calamites_ was recognised by laymen many years before specialists shared this view. One of the most interesting and important of all the older records of _Calamites_ is that published by Suckow[584] in 1784. Suckow is usually quoted as the author of the generic name _Calamites_; he does not attempt any diagnosis of the plant, but merely speaks of the specimens he is describing as “Calamiten.” The examples figured in this classic paper are characteristic casts from the Coal-Measures of Western Germany. Suckow describes them as ribbed stems, which were found in an oblique position in the strata and termed by the workmen Jupiter’s nails (“Nägel”). Previous writers had regarded the fossils as casts of reeds, but Suckow correctly points out that the ribbed character is hardly consistent with the view that the casts are those of reeds or grasses. He goes on to say that the material filling up the hollow pith of a reed would not have impressed upon it a number of ribs and grooves such as occur on the Calamites. He considers it more probable that the casts are those of some well-developed tree, probably a foreign plant. _Equisetum giganteum_ L. is mentioned as a species with which _Calamites_ may be compared, although the stem of the Palaeozoic genus was much larger than that of the recent Horse-tail. The tree of which the Calamites are the casts must, he adds, have possessed a ribbed stem, and the bark must also have been marked by vertical ribs and grooves on its _inner face_. It is clear, therefore, that Suckow inclined to the view that _Calamites_ should be regarded as an _internal cast_ of a woody plant. Such an interpretation of the fossils was generally accepted by palaeobotanists only a comparatively few years ago, and the first suggestion of this view is usually attributed to Germar, Dawes, and other authors who wrote more than fifty years later than Suckow.