— _P. Phillipsii_, Brongniart, Hist. p. 304, Pl. CIX. fig. 1. This species is often confused[813] with _Todites Williamsoni_. The name _Pecopteris whitbiensis_ has been used by different writers for Jurassic fronds which are undoubtedly specifically distinct: specimens so named by Brongniart should be referred to _Todites Williamsoni_, while _P. whitbiensis_ of Lindley and Hutton[814] is Brongniart’s _Cladophlebis denticulata_. It is impossible to determine with accuracy the numerous examples described as _Pecopteris whitbiensis_, _Asplenium whitbiense_, _Cladophlebis Albertsii_ (a Wealden species[815]), _Asplenium_, or _Cladophlebis_, _nebbense_[816], etc., from Jurassic and Rhaetic strata. The _Cladophlebis denticulata_ form of frond is one of the commonest in recent ferns; it is represented by such species as _Onoclea Struthopteris_, _Pteris arguta_, _Sadleria sp._, _Gleichenia dubia_, _Alsophila lunulata_, _Cyathea dealbata_, and species of _Polypodium_. It is, therefore, not surprising to find records of this Mesozoic species from many localities and horizons. All that we can do is to point out what appear to be the most probable cases of identity among the numerous examples of fronds of this type from Mesozoic rocks, particularly Rhaetic and Jurassic, in different parts of the world. The name _Cladophlebis denticulata_ may be employed in a comprehensive sense for fronds showing the following characters:— Leaf large, bipinnate, with long spreading pinnae borne on a comparatively slender rachis. Pinnules, in nearly all cases, sterile, reaching a length of 3–4cm., acutely pointed, finely denticulate or entire, attached by the whole of the base (fig. 257). In the apical region the pinnules become shorter and broader. Venation of the _Cladophlebis_ type (fig. 256, A). Fertile pinnules rather straighter than the sterile, characterised by linear sori parallel to the lateral veins (fig. 258).