It is proposed to restrict the name _Rhabdocarpus_[947] to impressions and casts of seeds of the type represented by _R. tunicatus_ as figured by Berger[948] and reproduced in fig. 506, K, the term _Rhabdospermum_ being applied to seeds of similar form in which are shown certain distinguishing anatomical features. _Rhabdocarpus tunicatus_ Berger is a species founded on a specimen from the Coal Measures of Silesia characterised by an outer carbonised testa prolonged apically as a blunt snout and, as seen in fig. 506, K, covering an apparently ribbed nucule, but the ‘ribs’ are due to the presence of fibrous strands and are not ribs in the ordinary sense. The outer tissue shows numerous longitudinal striations due presumably to the presence of fibrous elements in the sarcotesta like those shown in the petrified seed represented in fig. 501, C. The genus is defined by Berger as follows: ‘Semina ovata vel elliptico-oblonga secundum longitudinem parallele nervosa vel tenuissime striata, putamine (interdum deficiente) instructa.’ As used by Berger and many other authors _Rhabdocarpus_ includes a miscellaneous collection of seeds often differing widely from the type-species. Many of the examples correctly referred to Berger’s genus are platyspermic though a bilateral symmetry is by no means always clear. Renault and Zeiller[949] in their definition of _Rhabdocarpus_ include bilateral symmetry as a characteristic feature and speak of the seeds as oblong or oval with a pointed or truncate apex and a rounded base. Impressions of _Rhabdocarpus_ differ from those of _Cardiocarpus_ or _Cordaicarpus_ in their more elongate form, always longer than broad, and in the absence of a basal sinus. The seeds found attached to _Neuropteris_ pinnae and, in external features, agreeing with many specimens included in Berger’s genus, have been transferred by P. Bertrand[950] and Arber[951] to a new genus _Neurospermum_[952]. Arber[953] in his recent revision of British seeds proposes to restrict the name _Rhabdocarpus_ to platyspermic seeds having a ‘large unsymmetrical nucule enclosed in a large unsymmetrical wing or sarcotesta,’ that is to forms symmetrical in one plane. In this category he includes _Rhabdocarpus tunicatus_ Berg. (fig. 506, K) and _R. subtunicatus_[954] Grand’Eury, but it is not clear on what grounds Berger’s species is spoken of as symmetrical in only one plane: in the species _R. Lilleanus_ Arb.[955] the symmetry is hardly sufficiently well defined to rank as a generic character. In the case of the _Neuropteris_ seeds the apical snout is slightly curved, thus giving them an unsymmetrical appearance (cf. fig. 422, p. 114). The Carboniferous and Permian seeds usually referred to _Rhabdocarpus_ are transferred by Arber to his genus _Platyspermum_[956], a designation for which it is proposed to substitute Nathorst’s genus _Holcospermum_[957]. In seeds preserved as more or less flattened impressions it is practically impossible in many cases accurately to