14 



with elongate ridges pointed below and bifurcate above, 

 differing in size and form on branches of different sizes. 

 Branches or younger stems with nodes bearing a 

 whorl of prominences projecting beyond the general sur- 

 face. 



Stem consisting of a pith-cylinder somewhat Sternbergian 

 in structure, and formed of cellular tissue denser at the 

 surface and with traces of detached vascular bundles. 

 Woody cylinder with fibres having one row of pores 

 and frequent medullary rays of few rows of cells superim- 

 posed. 



Foliage borne spirally on pinnate (?) branchlets. Leaves 

 elongate, oblong, acutely pointed, narrowed and decurrent 

 at base, with a midrib and two side nerves, possibly resin 

 ducts. Fruit borne laterally on the branches, and consist- 

 ing of four large seeds, rounded without, and wec^ge-shaped 

 within, so that in outline they have a semi lunar form. 

 They seem to have been enclosed in an involucre. 



Should it prove that the nodose and non-nodose stems are 

 specifically distinct, and that the leaves and fruit above 

 described belong to the latter, the description of the stem 

 will require a slight modification in that sense. 



It would appear that in Tylodendron we have a gymno- 

 spermous type akin to the Taxinese, and which was charac- 

 teristic of the Permian, apparently extending also into the 

 Triassic Period. 



We may now turn to the consideration of what is known 

 of Palaeozoic gymnosperms allied to the forms above 

 noticed, with the view of ascertaining their position in the 

 classification, and clearing up some doubtful points arising 

 from the fragmentary condition of our materials. 



In the first part of the " Flore du Monde Primitif " (1820) 

 Sternberg describes and figures, under the names Flabellaria 

 borassifolia and F. palmata, two groups of leaves from the 

 Coal Formation, both apparently referable to the species 

 now known as Cordaites borassifolia. Leaves of this kind 

 have since been found very abundantly in the Carboniferous 



