11 



phragms characteristic of Sternbergia. In other examples 

 this is less pronounced or absent. The pith is composed of 

 ordinary parenchymatous tissue, becoming more dense 

 toward the outer surface, and especially in the prominences 

 corresponding to the exterior ridges. In each of these there 

 is also a vacant canal, and similar canals appear in a verti- 

 cal position in the interior of the pith, as if there had been 

 vessels dispersed through the pith and sending off bundles 

 to the exterior prominences. In some specimens, shreds of 

 woody tissue appear at the surface of the pith, and in 

 others, in which the pith is not preserved, the woody cylin- 

 der shows its character somewhat perfectly. In the cross 

 section it presents square meshes in radiating rows, not dis- 

 tinguishable from those of Dadoxylon. In the longitudi- 

 nal section, however, the tissue is seen to be thin-walled, 

 with very indistinct disks, which so far as observed, appear 

 to be in a single row, in which respect they differ some- 

 what from those observed by Weiss, which varied from one 

 to three rows, and with frequent medullary rays, simple 

 and composed of few cells superimposed, in which respect, 

 as well as in the disks, they differ 

 from those of Dadoxylon materi- 

 arium the species found with them 

 in the Permian sandstones of 

 Prince Edward Island. In the 

 nodose specimens, the woody fibres 

 are very small, and in the nodes, 

 become tortuous and interlaced in 

 the manner described by William- 

 son in the nodes of Calamites. In 

 the non-nodose form the tissue is 

 more open and very thin-walled. 

 Nothing is known of the structure 

 of the outer bark except impres- 

 sions of its form with elongated 

 leaf-bases different from the mark- 

 ings on the internal surfaces. 

 (Fig. 4.) With reference to the latter it would seem that they 



FIG. 4. Leaf-base and outer 

 surface of Tylodendron 

 with fruit scars. (Drawn 

 by Mr. Bain.) 



