The type-species, from North America and Europe, is characterised by its shovel-like lamina from 3 to 6 cm. long closely resembling in shape some lepidopterous scales; the surface is ribbed, each rib corresponding to a tooth on the distal margin; on each of the parallel ridges are 4–5 longitudinal lines indicating either veins or stereome strands (fig. 428, A, C). The examination of preparations made by Dr Kidston from a leaflet of this species enables me to add a few facts with regard to the microspores. The spores, which cover almost the whole surface of the lamina, show a tendency to a more or less definite arrangement in longitudinal rows. Two types of cuticularised membrane are represented among the associated fragments: in some pieces of cuticle the cells are short and have straight walls while in others the preservation is inferior and the cells appear to be longer and narrower. One or both of these membranes probably belong to the sporangia. The oval slit, which is a striking feature on several of the spores (fig. 429), points to their bilateral nature and dehiscence along the major axis. A comparison of these spores with those obtained by Kidston from the English species _Whittleseya fertilis_ reveals a very close agreement both in size and shape and confirms the identification of the Staffordshire specimens as leaflets of _Whittleseya_. The large size of the microspores and the gaping oval aperture in some of them are features in which they agree closely with the spores of _Dolerophyllum fertile_ described by Renault[364]. In both cases the spores tend to be arranged in long groups and they are practically identical in form and in the nature of the exine; those of _Dolerophyllum_ are 280μ long while those of _W. fertilis_ reach a length of 220μ. In some of the _Whittleseya_ spores the exine has split as in the specimen shown in fig. 429, but in others there are two curved lines along which dehiscence has begun, a character in which the spores appear to be identical with those of _Dolerophyllum_ described by Renault who speaks of dehiscence by means of an operculum. There is, I venture to think, little doubt as to the very close affinity of the two types. The systematic position of _Dolerophyllum_ is not certainly established; if the generic identity of the leaves described as _D. Berthieri_ Ren. and the petrified specimens named _D. fertile_ is assumed, it is a legitimate inference that the genus is founded on fertile pinnules of a Pteridosperm with foliage of the _Neuropteris_ or _Cyclopteris_ form. It would seem probable that both _Whittleseya_ and _Dolerophyllum_ _fertile_ are microspore-bearing leaflets of Pteridosperms, possibly of some Medullosan plants. The leaflets of _Whittleseya_ agree in form fairly closely with those of _Potoniea adiantiformis_ Zeill. described on a previous page[365] as the male organs of a Pteridosperm.