8 Weiss, A Tylodendron-Uke Fossil. 



The leaf-traces which are given off from the base of 

 the fohar gaps are of fair size and are not quite median 

 in their insertion, but seem to be attached for a short 

 distance to one side of the gap. They run vertically for 

 some distance, about '3 of the. length of the foliar gap, 

 and can be seen to consist of two distinct branches 

 separated by parench}'matous tissue. Towards the base 

 these two strands join and then fuse laterally with the xy- 

 lem mass of the stem. Each branch has a small group of 

 central tracheids, sometimes separated from the regularly 

 arranged rows of secondary tracheids. In transverse 

 sections it was not possible to determine the position of 

 the protoxylem owing to the slight differentiation in 

 the size of the tracheids, but a good longitudinal section 

 indicated an endarch arrangement. After running verti- 

 cally upwards for some distance, the leaf-trace bundles 

 bend sharply outwards, and can no longer be followed in 

 the specimen, which is limited to the pith and the adjacent 

 tissues. 



From the foregoing description of our specimen it 

 will be seen that it agrees, in the main, with other Tylo- 

 dendra, but it is not possible to be quite definite as to the 

 systematic position of the plant to which it belonged. 



As stated at the commencement of this paper, Potonie 

 definitely identified the Tylodendron remains originally 

 described by Weiss and re-examined by himself as pith 

 casts belonging to the stems o{ Araucarioxylon Rhodeanuui, 

 which itself was probably the stem of the genus Walchia 

 of Sternberg. At all events Tylodendron was the pith of 

 an Araucarian tree. Seward' found somewhat similar 

 pith casts, but devoid of periodic dwellings, which he 

 correlated with the genus Voltzia heterophylla, which is 



'■ Seward, A. C. " lylodeudnm and Voltzia.'' Geol. Magazine, Decade 

 iii., vol. vii., No. 311, May, 1890. 



