The platyspermic seeds included in this genus agree in size and form with impressions assigned to _Rhabdocarpus_ and as regards the main features conform anatomically to _Cardiocarpus_; they were probably borne on Cordaitean plants. Fig. 501, C, represents a longitudinal section of the species _Rhabdospermum cyclocaryon_ described by Brongniart as _Rhabdocarpus cyclocaryon_: the sarcotesta is particularly well developed in the apical region; at the apex a portion of the micropyle is seen at _m_ and near the nucellus are pieces of the sclerotesta shown in black. The presence of anastomosing fibres near the surface is a characteristic feature: these, as Bertrand points out, do not form a hypodermal tissue in the strict sense as they may be separated by some of the thin-walled parenchyma of the sarcotesta from the epidermis. The sclerotesta is only partially preserved but the inner portion forms a dark line enclosing the nucellus, the superficial tissue of which is separated from the shrunken prothallus represented by the almost spherical dotted region: the remains of an archegonium are seen at _a_ (fig. 501, C) and the characteristic tent-pole apex of the prothallus is shown at _b_. While in shape and in the general plan of organisation _Rhabdospermum_ agrees with _Cardiocarpus_, the vascular system in the chalazal region constitutes a distinguishing feature. In _Rhabdospermum_ the main vascular strand passes through the sclerotesta, _e_, _e′_, fig. 501, E, before giving off two bundles which bend back (‘faisceaux récurrents’), traverse the shell, and then pass up the sarcotesta in correspondence with the feebly developed lateral keels as far as the micropyle, while in _Cardiocarpus_ (fig. 500, B) the bundles are given off before the main strand reaches the sclerotesta. Similar recurrent bundles occur also in _Mitrospermum_ (fig. 494, K)[967]. =Mitrospermum.= A. Arber.