344 CARDIOCARPALES [CH. 



transferred to Neurospermum, that belong to Pteridosperms. 

 A species, Rhabdocarpus Oliveri, recently described by Kidston^ 

 from the Staffordshire coalfield is an example of a radiospermic 

 seed which may be assigned to a Pteridosperm. The type-speci- 

 men is an ovate seed 4 cm. long and 2 cm. broad agreeing in form 

 and surface-features with Rhdbdocarpus as already defined, but 

 the evidence it affords of internal structure is insufficient to 

 determine its position with regard to genera founded on anatomical 

 characters. Other examples of Rhabdocarpus are described by 

 Lesquereux^ and White* from American Coal Measures, by 

 Grand'Eury* from the Loire, by Renault^ from Autun, and by 

 many other authors. 



Rhabdospermum. Gen. nov. 



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, repre- 

 sents a longitudinal section of the species Rhabdospermum cyclo- 

 caryon 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 hne 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 distin- 

 guishing feature. In Rhabdospermum the main vascular strand 



1 Kidston (14) PI. xvi. figs. 6—8. 



" Lesquereux (80) A. p. 574. ^ White (99) B. p. 267. 



* Grand'Eury (77) A. PI. xv. ' Renault (93) A. PI. lxxxvi. 



