CONTRIBUTIONS TO OUR KNOWLEDGE OF BRITISH PALEOZOIC PLANTS. 715 



Sigillaria Strivelensis Kidston, n. sp. (PI. I, figs, l, 2, 3, 3a, 4, 4a, 5, 5a.) 



Description. — Stem ribbed, ribs slightly convex, furrows strongly undulated. 

 Leaf scars placed at the top of the inflations, with their lateral angles at the widest 

 part and occupying almost the entire width of the rib, more or less distant, penta- 

 gonal, notched on upper margin, basal margin pointed, rarely rounded, lateral angles 

 slightly above the centre, prominent, short, and quickly reaching the furrow ; cica- 

 tricules placed a little above the centre of the leaf scar, the central (vascular) 

 transversely lunate or punctiform, the lateral (parichnos) on the same level, elongate, 

 slightly diverging. Outer surface of ribs ornamented with three lines of diverging 

 transverse bars (rarely uniting to form a single central band), which, descending 

 from the base of the leaf scar, gradually broaden out till they reach the top of the 

 leaf scar below. Immediately above the leaf scar, and arising from the notch, is a 

 plumose arrangement of fine ridges. Ligule pit not observable. Subcortical condition 

 finely striated longitudinally. 



Remarks. — As there is apparently here either an abnormal elongation of the 

 cortex between the leaf scars in some of the specimens or a reduction in its extent in 

 others, as shown by the varying distances which, separate them, it is not possible to 

 determine which is the normal form of the species. It has therefore been deemed 

 best to accept provisionally a middle condition and describe it first. This is seen at 

 figs. 1, 2, PI. I, which are both enlarged two times. Fig. 1 shows the undulations of 

 the furrows, with the leaf scars, which are about their own height apart, placed on 

 the expanded portion of the rib. ' They occupy almost its whole width, having only a 

 narrow band of cortex between their lateral angles and the furrow, which the descend- 

 ing ridges springing from the lateral angles speedily reach. The leaf scars are 

 distinctly notched on their upper margin and some of them rounded at their base, 

 though others are more pointed. The three diverging and broadening lines of 

 ornamentation which descend from the base of the leaf scar abut against the top of 

 the scar lying below. Immediately above the leaf scar indications of the small 

 plume-like ornamentation can be seen to spring from the notch. The small example 

 given at fig. 2 is very similar, only the leaf scars are slightly more distant and, with 

 the exception of the lowest one seen in the figure, which is somewhat rounded below, 

 fche basal margin of all the others ends in a point. The plume-like marking above the 

 leaf scar is well seen on this example. In all cases the leaf cushions : _ have formed 

 prominent and probably considerably elevated bracket-like structures, their upper 

 margins forming the base of an upward-rising surface to which the leaf was 

 attached. On the specimen given at fig. 3, of which a portion is enlarged two times 

 at fig. 3a, the leaf scars are less than their length apart and the inflations and con- 

 tractions of the ribs become more marked. Owing to pressure, the interfoliar area 

 seems to be pressed over the upper margin of the leaf scar, frequently obscuring the 

 " notch " and hiding the plumose marking. On most of the interfoliar areas, the 



