This species is chosen as an example of a French _Equisetites_ of Permian age. It was recently founded by Zeiller[504] on some specimens of imperfect leaf-sheaths, and defined as follows:— Sheaths spreading, erect, formed of numerous uninerved coherent leaves, convex on the dorsal surface, spatulate in form, 5–6 cm. in length and 2–3 mm. broad at the base, and 5–10 mm. broad at the apex, rounded at the distal end. The specimen shown in fig. 58, _A_, represents part of a flattened sheath, the narrower crenulated end being the base of the sheath. The limits of the coherent segments and the position of the veins are clearly marked. Zeiller’s description accurately represents the character of the sheaths. They agree closely with an Equisetaceous leaf-sheath, but as I have already pointed out, we cannot feel certain that sheaths of this kind were not originally attached to a Calamite stem. The portion of a leaf-sheath and a diaphragm represented in fig. 57, _B_, agrees closely with Zeiller’s examples. This specimen is from the English Coal-Measures, but it is not advisable to attempt any specific diagnosis on such fragmentary material. It is questionable, indeed, if these detached fossil leaf-sheaths should be designated by specific names. Another similar form of sheath, hardly distinguishable from Zeiller’s species, has recently been described by Potonié from the Permian (Rothliegende) of Thuringia. [Illustration: FIG. 58. _A._ _Equisetites spatulatus_, Zeill. Leaf-sheath. ⅘ nat. size. (After Zeiller.) _B._ _E. columnaris_, Brongn. From a specimen in the British Museum. ¾ nat. size. _C._ _Equisetum ramosissimum_, Desf. × 2. _D._ _Annularia stellata_ (Schloth.). Leaf-sheath. Slightly enlarged. (After Potonié.) _E._ _Equisetites zeaeformis_ (Schloth.). Leaf-sheath. ⅘ nat. size. (After Potonié.) _F._ _E. lateralis_, Phill. From a specimen in the Scarborough Museum. Nat. size.] 3. _Equisetites zeaeformis_ (Schloth.)[505] Fig. 58, _E_. The sheaths consist of linear segments fused laterally as in _Equisetum_. In some specimens the component parts of the sheath are more or less separate from one another, and in this form they are apparently identical with the leaves of _Calamites_ (_Calamitina_) _varians_, Sternb. The example shown in fig. 58, _E_ is probably a young leaf-sheath; the segments are fused, and each is traversed by a single vein represented by a dark line in the figure. The regular crenulated lower margin is the base of the sheath, and corresponds to the upper portion of fig. 58, _A_. This species affords, therefore, an interesting illustration of the difficulty of separating _Equisetites_ leaves from those of true _Calamites_. Potonié has suggested that the leaf-sheath of a young Calamite might well be split up into distinct linear segments as the result of the increase in girth of the stem. • • • • •