_Cordaites principalis_ occurs in both Carboniferous and Permian strata. The leaves described by Lesquereux[575] from Pennsylvania as _C. Mansfieldi_ agree closely with _C. principalis_. Another similar or possibly identical form is represented by _C. Ottonis_ Gein.[576] _Cordaites borassifolius_ (Sternberg). The leaves of this species, originally referred to _Flabellaria_[577], resemble those of _C. principalis_ but differ in the ovate-lanceolate and less obtuse apex and in the presence of only one or rarely two finer striations between the stronger ribs. Corda’s drawing[578] affords a good illustration of the crowded spiral disposition of the foliage comparable with that on an _Agathis_ shoot. The lamina is usually 4–8 cm. broad but in exceptional cases may reach a breadth of 12 cm. The species occurs in the Coal Measures, especially in the Westphalian series and in Permian rocks. Feistmantel[579] unites with this type _Cordaianthus Pitcairniae_ (fig. 480, A), but as in other cases there may be a confusion between _C. borassifolius_ and _C. principalis_. Leaves described by Lesquereux as _C. communis_[580] are, as White says, not distinguished by any well-marked characters from this species. White[581] figures some good examples of _C. borassifolius_ from Missouri, reaching in one case a length of 40 cm., showing on the lamina the fructifications of a fungus, _Hysterites cordaitis_[582] Grand’Eury. The leaves described from Canada and the United States as _C. Robbii_[583] Daws. are closely allied to if not identical with Sternberg’s type. Among other species differing in no definite character from _C. borassifolius_ is _C. lancifolius_ described by Schmalhausen[584] from the Permian of Russia. _Cordaites lingulatus_ Grand’Eury. The leaves of this species[585] are characterised by the obovate lamina and bluntly rounded or almost truncate apex; it affords a good illustration of the uncertainty of the ribbing as a diagnostic character. The lamina of a well-preserved specimen from the Blanzy coalfield described by Zeiller[586] reaches a length of 35 cm. and a breadth of 10–11 cm. decreasing to 4 cm. at the base (fig. 467). In the lower part of the lamina Zeiller describes the ribs as unequal in prominence, the stronger ones being separated by 1–3 finer ribs, while in the middle and upper portions the ribs appear to be of equal size. Some of the finer ribs are due to folding of the lamina and are not represented, as are the ribs due to the presence of stereome-strands, by dark streaks in the detached cuticle. [Illustration: Fig. 467. _Cordaites lingulatus._ (After Zeiller; ⅚ nat. size.)] Reference has already been made to the anatomical features of leaves of this species described by Lignier[587] and other authors. _Cordaites grandifolius_ Lesquereux.