232 FLOEA OF LOWER COAL MEASURES OF MISSOURL 



lougitudinal areoles, flexuose, and coursing from either of the four sides 

 of every rhomboidal leaf scar toward the proximal side of the correspond- 

 ing leaf scar, so that the principal and most conspicuous strands radiate 

 from each leaf scar to the four nearest scars, the intermediate strands in the 

 rhomboidal areas thus formed tending toward parallelism with the border 

 that is nearest; foliar cicatrices borne on small bolsters, more or less distant, 

 usually quite distant, probably in vertical rows, though plainly aifecting a 

 spiral arrangement, varying greatly in angle even in the same segment, 

 transversely rhomboidal, with the lateral angles very acute and more or less 

 prolonged, varying in altitude, the margins more concave in the vertically 

 broader scars, or nearly straight in the vertically narrow forms, rounded 

 below, often more or less distinctly emarginate at the uppei- edge, which is 

 bordered above by a narrow, smooth, somewhat crescentic zone nearly one- 

 half the altitude of the leaf scar, the convex, truncate-rounded margin 

 upward, the wings or lateral angles tapering to the lateral angles of the 

 scar, the upper border indented by a V-shaped depression which reaches 

 nearly to the upper margin of the leaf scar and includes the suprafoliar 

 punctiform trace; bolsters fusiform-triangular in a longitudinal sense, the 

 broader end, narrower than the superimposed leaf scar, being upward and 

 more prominent, while the lower end vanishes as an oblique section of a 

 cylinder at the level of the cortex; surface of the bolster below the leaf scar 

 and contiguous thereto bearing a thin, downward-rounded apronlike field, 

 the lower margin of which is nearly semicircular; vascular trace small, 

 situated near to or a little alcove the middle of the leaf scar, punctiform or 

 slightly elongated horizontally ; lateral cicatricules a little distant on each 

 side, narrow, linear-crescentic, nearly meeting both above and below the 

 vascular trace, often ha^^ng the appearance of, if not actually forming a 

 ring or slightly obovate cicatricule, reaching nearly to the upper and lower 

 margins of the leaf scars; partially decorticated stems, showing the rough 

 striations less distinctly, substriate, and presenting only the somewhat linear- 

 triangular outlines of the bolsters, marked by the cicatricular ring, the leaf 

 scar and its superior and inferior fields being removed with the cuticle, or, 

 when further stripped, revealing a Knorria form, the blunt, slightly promi- 

 nent upper ends of the narrow, distant elevations corresponding to the 

 vascular traces, while the intermediate surface is minutely and irregularly 

 striated. 



