Before Weiss proposed the term _Calamitina_, various authors had figured this form of Calamite under a distinct generic name (_e.g._ _Hippurites_ of Lindley and Hutton[779], _Cyclocladia_[780], _Macrostachya_[781], &c.). Stems of this type have also been described by more recent writers under different names, and considerable confusion has been caused by the use of numerous generic designations for forms of _Calamitina_. Some small fragments of _Calamitina_ stems were described by Salter[782] in 1863 as portions of a new species of the Crustacean _Eurypterus_ (_E. mammatus_). In 1869 Grand’Eury proposed the generic name _Calamophyllites_[783] for stems bearing verticils of _Asterophyllites_ shoots; his description of such stems agrees with Weiss’ _Calamitina_, but as Grand’Eury’s name is used in a narrower sense as implying a connection with _Asterophyllites_, it is more convenient to adopt Weiss’ term in spite of the priority of _Calamophyllites_. In the _Fossil flora of Commentry_ we find some flattened stems of the _Calamitina_ type described under different generic names, as _Arthropitys approximatus_[784] and as _Macrostachya_[785]. The determination of distinct species of the sub-genus _Calamitina_ is rendered almost hopeless by the variation in the different branches of the same individual, and by the difficulty of connecting surface-impressions with casts of the pith-cavity. A typical example of the _Calamitina_ type of _Calamites_ was figured by Sternberg[786] in 1821 as _Calamites varians_. This has been adopted by Weiss[787] as a comprehensive species including several different ‘forms’ of stems, which differ from Sternberg’s fossil in such points as the number of nodes between the branch-whorls and the number of branches in each whorl. The result of this system of nomenclature is the separation of portions of one specific type under different form-names. It must be clearly recognised that accurate specific diagnoses are practically impossible when we have to deal with fragments of plants, some of which are mere pith-casts, while others show the surface features. The specimen represented in fig. 99 agrees with a stem described by Ettingshausen[788] in 1855 as _Calamites Göpperti_, and as a matter of convenience a member of the _Calamitina_ group showing such characters may be referred to as _Calamites_ (_Calamitina_) _Göpperti_ (Ett.). The following list, which includes a few synonyms of this form, may suffice to illustrate the difficulties connected with accurate systematic determinations. _Calamites_ (_Calamitina_) _Göpperti_ (Ett.). Fig. 99.