Manchester Memoirs, Vol. hi. (191 2), No. IT. 3 



the carbonaceous layer which is still adherent where the 

 fossil has not been exposed to weathering. Where this 

 clings, the sharp outline of the markings is obscured, and 

 a smoother surface results. Microscopic preparations of 

 fair-sized stems rarely show the cortex as retained : it 

 has quite naturally broken away along the zone of soft, 

 delicate tissue, which occupies the position assigned to 

 cambium and phloem. 



In the long internodes, the markings have the form of 

 very fine longitudinal striations distributed over the 

 entire surface, and so uniform in character throughout 

 that they cannot be regarded as wrinkles or cracks due to 

 shrinking or splitting bark. Ridge and furrow alternate, 

 but neither, as a rule, extends the full length of the 

 internode. The outstanding part is usually of a very 

 attenuated spindle shape, broader considerably in its 

 wider part than the furrow, dying out gradually, and 

 sliding as it were past the tapering ends of its neighbours. 

 The identification from structural examples is easy. 

 The ridges represent the secondary xylem broken up 

 into long slender sections by the furrows of the softer 

 tissue of the secondary medullary rays. From the 

 absence of parallel-sided ridges, extending from node to 

 node, we may conclude that in this species the secondary 

 xylem extended at the periphery completely across the 

 primary medullary rays. 



The short internodes differ somewhat. Where the 

 striations can be made out they are much broader than 

 in the others ; they are parallel-sided and unbroken 

 throughout the length of the internode : the separating 

 depressions are very narrow. The differences may be 

 due to uneven preservation, but it is more likely that 

 they indicate differences in the living plant : parts quite 

 free from distortion are clear to observation. 



