Manciiester Memoirs, Vol. Ivi. (191 2), No. lY. 5 



One type of oval or elliptical leaf, as seen in structural 

 preparations, corresponds very satisfactorily with these 

 surface features. As seen in many of the beautiful 

 examples which have been figured, there is present in the 

 leaf a central strand of vascular tissue associated with a 

 more or less complete surround of delicate-walled cells. 

 This fine-celled core is marked off from the rest of the 

 leaf by the firm and prominent ring of melasmatic tissue. 

 Undoubtedly this boundary line corresponds to the edge 

 of our central pit, which was the line of passage of the 

 leaf-trace into the secondary xylem of the stem. In the 

 pit itself would lie the xylem, phloem, and parenchyma 

 (if any) of the leaf-trace, whilst the melasmatic ring of 

 the leaf would be continuous with the corresponding 

 tissue in the stem. 



When decay of the plant set in and the leaves and 

 branches fell away, it would be natural that the slender 

 vascular strand with its weak ground tissue should break 

 off, leaving a depression to be filled in by the mud in 

 which the whole was embedded. This in turn has been 

 removed and the cavity has again been left exposed. 

 Beyond the bundle tract would lie the cortical paren- 

 chyma — against the area of the slanting surface {U). 



Branch Scars. The lower branching node produces 

 nine and the upper, eight branches. These numbers refer 

 only to what are visible on a single flat face, and the pro- 

 bable total in each whorl would be about twenty, or rather 

 less than half the estimated number of leaves. It is not 

 possible to trace any regularity in the occurrence of 

 branches relatively to leaf-traces. 



The scars are crowded together, the boundary rim 

 being common to each pair at the point where they 

 touch. 



