330 Systematic Paleontology 



axis of the trunk of nearly 45°; rows of scars very distinct, spirally 

 arranged around the trunk, those from left to right making an angle 

 with the vertical axis of about 45°, those from right to left of about 

 30°, the latter much the more obvious and curving upward, so that the 

 angle varies from 45° below to 25° above; leaf scars subrhombic, the t^TO 

 upper ones often forming a gentle arch, sometimes nearly a horizontal 

 line, making the alveoli true triangles, the lower 2 cm,, the upper 12 mm. 

 wide, about 1 cm. high, diminishing toward the summit; leaf bases 

 usually present, soft, shady, and fine grained; rarely reaching the sur- 

 face, generally sunk to a depth of 5 mm., sometimes of 2 cm.; vascular 

 bundles often visible, either as slight protuberances on the ends of those 

 leaf bases that rise highest in the scars, or as small dots on those that 

 lie deeper, or as a series of ridges running down into the scars where 

 the central portion is deeper than the outer portion, the rows 0.5 mm. 

 from the outer margin with occasional faint traces of more central 

 bundles ; ramentum walls when normal about 5 mm. thick, of a rather 

 firm consistency, presenting a continuous sharp ridge in the direction of 

 the rows of sears from right to left, without visible commissure; repro- 

 ductive organs abundant, one in the axil of each leaf, small and doubt- 

 less mostly abortive, occupying wide triangular spaces between the leaf 

 scars, causing the walls to appear abnormally thick; spadjces always 

 present and flush with the walls, elliptical or circular in cros.s- section, 

 the larger ones 2 cm. wide and 1 cm. high, often much smaller ; involucral 

 scales abundant,- occupying most of the space between the walls, con- 

 centrically arranged in groups of thin, crescent-shaped scars, which are 

 always somewhat depressed and contain the bases of the scales ; essential 

 organs visible at the center of the best preserved spadices, but often want- 

 ing and represented by a cavity; armor 3 cm. thick; woody cylinder con-, 

 sisting of two layers or rings, the' outer, or cortical parenchyma 2 cm. 

 thick, open and loose in structure, the large vascular strands passing 

 upward and outward through it to enter the leaf bases, where they sud- 

 denly arch over and assume the downward course of the leaves, the inner 

 or fibrous zone, 5 mm. thick, very distinct from the outer, the strands 

 rising from its outer surface and not penetrating it, its fibres being 



