92 CYCADEAE, MEDULLOSEAE. 



the figures, one described by Brongniart l as Endogenites echinatus, from 

 the coarse limestone of the Eocene deposits of Soissons, and another 

 Cycadites Escheri, Heer 2 , from the Molasse of Stein near Schaffhausen. On 

 the other hand, stems and fragments of stems occur in the Upper Coal- 

 measures and in the Rothliegende in Saxony, Bohemia, the neighbourhood 

 of Autun, and in the Ural Mountains, the structure of which points to their 

 affinity with the Cycadeae, while the surface-characters cannot be recognised 

 at all or only imperfectly. Since Cotta's 3 time they have been known as 

 Medullosae, and they must be noticed again when the Mesozoic forms just 

 mentioned have first been considered. 



As a rule the Mesozoic stems of Cycadeae, which, as was said, are 

 shortly cylindrical or roundish and tuber-like in form, show only the 

 characters of their surface, which is covered as in living species with closely 

 crowded spirally disposed leaf-bases and scale-leaves. The form and 

 surface characters of the stems were used to limit the purely conventional 

 generic groups, to which Saporta has given entirely new names, because 

 those previously in use, Mantellia, Brongn., Bucklandia, Brongn., Clathraria, 

 Mantell, included many remains not belonging to the group, and were in some 

 cases founded upon them. Saporta places all tuber-like and spherical stems 

 with their close armour of scales and leaf-scars which are rhombic on the cross 

 section in his genera Bolbopodium and Clathropodium. These genera are 

 represented by a considerable number of species and vary much in size. If 

 they are small we may easily be in doubt, as has been already said, whether 

 we are dealing with stems or fruits, as for example in the greater part of 

 the remains figured by Carruthers 4 as Cycadostrobus. C. Brunoni, Carr., of 

 unknown origin, is the only certain cone, but it looks more like a cone of 

 Araucaria than of Cycadeae. In some forms figured by Saporta f> the ring 

 of wood is clearly to be seen when the fossil is broken across, as in Clathro- 

 podium Trigeri, Sap., found near Le Mans but not in its original place of 

 deposit, and in C. Sarlatense, Sap., also a stray object picked up near 

 Sarlat in the Dordogne. To judge from the figure there might be several 

 consecutive rings of wood in this stem, as in old specimens of Cycas, and 

 this point should be attended to in any further examination of the fossil. 

 Its medulla is of remarkably small diameter. The stem described by 

 Carruthers 6 as Bennettites Saxbyanus is also referred by Saporta to 

 Clathropodium, and this from his stand-point is quite justifiable. But this 

 stem does really belong to Bennettites, Carr., for though the lateral axes 

 so characteristic of this genus are not to be seen in the figure, yet Car- 

 ruthers states that they are a general feature in all the species, and I have 

 satisfied myself by personal examination that they are present in the three 



1 Brongniart (3), p. 301 ; t. 16, f. 2. ' 2 Heer (3), vol. i, t. 15. 3 Cotta (1). 4 Carruthers (1). 

 5 de Saporta (4), vol. ii, tt. 122, 123. Carruthers (4), t. 57. 



