456 MESOZOIC FLORAS OF UNITED STATES. 



Ctcadeoidea Bibbinsi Ward. 



PI. LXXXIII, Fig. 3; PI. LXXXIV, Fig. .3; PL LXXXV; PI. LXXXVII, Figs. 

 I, 2, 4, 6, 7; 11, 1, 2, 4, 8, 9, 10, 11; in, 5, 7; iv, 2, 3, 6, 8, 11; v, 12, 15; PI. 

 LXXXIX, Figs. I, 5; ii, 2, 5, 6; PI. CI-CIV. 



1897. Cycadeoidea Bihbinsi Ward: Proc. Biol. Soc. Washington, Vol. XI, p. 1.5. 



Trunks large, 40 cm. to 60 cm. high, laterally compressed, girth of 

 largest specimen 1 meter, of next in size 88 cm., shorter axis of cross 

 section one-half to two-thirds of longer axis, contracted toward the 

 summit, terminating in a conical bud 30 cm. high, or, where this is want- 

 ing, in a concave depression, thoroughly silicified throughout, heavy 

 and solid, of a dark color; all the organs of the armor nearly at right 

 angles to the axis of the trunk; leaf scars arranged spirally around the 

 trunk in imperfect quincuncial order, subrhombic, the lower angle much 

 sharper than the upper, the latter sometimes reduced to a curve, 14 

 mm. high, 26 mm. wide; ramentum walls moderately thick, usually 

 solid ; vascular bundles of the petioles arranged in a row entirely around 

 them and near the margin of a cross section, also sometimes a few near 

 the center; spadices abundant, irregularly scattered over all parts of 

 the surface, usually showing the marks left by the essential floral organs 

 or a central cavity occupying their place, surrounded by curved or 

 crescent-shaped pits concentricallj' arranged in several rows and set 

 concave to the axis of the spadix, representing the involucral bracts; 

 armor varying from 25 mm. to 75 mm. in thickness, this variation often 

 great in different parts of the same specimen; cambium layer indistinct; 

 liber zone not generally distinguishable from the wood; the latter in 

 two or three zones, medullary rays faint; medulla well marked, homo- 

 geneous, usually spongy in appearance. 



This species represents a type quite distinct from all the others, 

 and the cycadean trunks of the iron-ore deposits of Maryland might 

 be divided into two classes, one of which should embrace all the forms 

 included in the six species above described, and the other those that 

 have been referred to this species. The fact that the rock in the latter 

 is always firm, hard, and heavy and usually dark colored is not merely 

 an accident of preservation, but results in some obscure way from the 

 nature of the vegetable tissues. The trunks are generally larger and 

 the leaf scars much larger, though they have nearly the same form and 



