486 STUDIES IN FOSSIL BOTANY 



ferred the species discovered by Nield to the type-genus 

 of the Cycadoxyleae, to which, as we shall now see, it 

 naturally belongs. 1 



The interest of the fossil depends on two points. 

 The first is the thoroughly Cycadean character of the 

 secondary wood, a character shown much more evidently 

 in this large stem, which in its dimensions is compar- 

 able to that of a recent Cycad, than in the smaller 

 stems of the Lyginodendreae. The second point is 

 the marked development of the anomalous medullary 

 vascular tissues, which we have already found, as an 

 individual peculiarity, in Lyginodendron oldhamium. 



A small stem, from the Lower Permian of Autun, 

 described by M. Renault, and named Cycadoxylon 

 Fremyi, shows still more perfectly the type of structure 

 just described. The stem is from 20 to 25 mm. in 

 diameter ; the cortex, which is fairly preserved, contains 

 gum-canals, and large pitted elements, probably with a 

 mechanical function. Within the cortex is a ring of 

 normal wood and bast, both well preserved, and exactly 

 resembling the vascular tissue of a modern Cycad. The 

 medullary rays are extremely wide, exceeding in extent 

 the tracheal bands between them. The tracheides are 

 for the most part pitted ; the bordered pits are ranged 

 in numerous series on the radial walls. Towards the 

 interior of the normal zone of wood, scalariform 



1 On Cycadoxylon robustum, see Williamson, " Organisation of the 

 Fossil Plants of the Coal-measures," Part iv., Phil. Trans. 1873, p. 386 ; 

 Williamson and Scott, "Further Observations," etc., Part iii., Phil. Trans. 

 vol. 186, B, 1895, p. 742; Seward, "A Contribution to our Knowledge of 

 Lyginodendron," Annals of Botany, vol. ix. 1897, p. 65. 



As Professor Seward points out, the specimen described by M. Renault 

 in the Flore fossile d 'Autun et oVEpinac, Part ii., under the name of 

 Medullosa gigas, appears to be almost identical with Nield's plant. 



