[Illustration: Fig. 501. A, _Cardiocarpus sclerotesta_ in longitudinal section; _pc_, pollen-chamber, _b_, tent-pole, _a_, archegonia. B, transverse section; _a_, archegonia. D, cast of the same or a similar type of seed. C, E, _Rhabdospermum cyclocaryon_, longitudinal section and a diagrammatic sketch of the seed-base; _m_, micropyle; _b_, tent-pole; _a_, archegonium. (A, B, C, after Brongniart; D, after Renault and Zeiller; E, adapted from Brongniart.)] =Cyclospermum.= Gen. nov. (= _Cyclocarpus_ Bertrand). As stated on a previous page Bertrand[943] re-establishes the generic name _Cyclocarpus_, founded on impressions without reference to anatomical characters, for two petrified seeds from St Étienne described by Brongniart as _Cardiocarpus tenuis_ and _Cyclocarpus nummularis_[944]. These types differ from _Rhabdospermum_ in the absence of an apical snout but agree with that genus in the steeply descending course of the vascular strands in the basal region of the seed. As stated on a previous page, the name _Cyclospermum_ is proposed as a substitute for _Cyclocarpus_ because of the employment of the latter term for impressions. =Cycadinocarpus.= Schimper[945]. _Cycadinocarpus augustudunensis_ (Brongniart[946]). In the possession of two sets of vascular bundles this type agrees with _Cardiocarpus_, but the more internal strands pass up on the inner face of the sclerotesta without penetrating into the nucellus, a feature in which _Cycadinocarpus_ agrees with the majority of recent cycadean seeds: the outer bundles are given off from the main supply after it has entered the sclerotesta and not before as in _Cardiocarpus_; they follow an oblique course in the sclerotesta and emerge into the sarcotesta at the shoulders of the basal curve of the seed. As in _Cardiocarpus_ and _Rhabdospermum_ the two outer bundles lie in the principal plane of the seed. There is a pollen-chamber at the apex of the nucellus and the latter tissue is prolonged as a tent-pole which engages with the micropyle. In the absence of data as to the course of the vascular bundles in the chalazal region it would not be possible to distinguish between this genus and _Cardiocarpus_. =Rhabdocarpus= Berger and =Rhabdospermum= gen. nov.