FOSSIL CYCADEAN TRUNKS FROM WYOMING 279 



the axis; woody zone i5iTim thick, not differentiated; medulla a thin 

 slab 3-6cm thick, 15cm wide, of a fine uniform structure resembling 

 the white iron ore of the Potomac beds of Maryland. 



Nos. 500.27, 500.32, and 500.64 are referred to this species. The 

 last is anomalous and shows relatively few of the characters, but it has 

 the same shape. The fruits are little elevated but otherwise this lead- 

 ing character holds for it. No. 500.27 is probably the top of the same 

 trunk as No. 500.32, but there is an interval between them, and they 

 have been subjected to different conditions since they became fossil- 

 ized. On a casual view, therefore, they do not seem so closely to re- 

 semble each other as they do when carefully inspected. They are 

 then found to have almost exactly the same width, thickness, and gen- 

 eral form, so that it is easy to see which sides correspond. All the 

 characters also agree except that the fruiting axes are more prominent 

 on No. 500.32, representing the lower portion. This is partly due to 

 the fact that this specimen has suffered more from erosion, and, owing 

 to the greater hardness of these organs, they are made to stand out 

 more conspicuously. It was the appearance thus produced that sug- 

 gested the specific name. 



No. 500.27 weighs 5.19, No. 500.32, 8.31, and No. 500.64, 4.68 

 kilograms. 



CYCADELLA JEJUNA n. sp. 



Trunks of medium size (i8cm high, 7— 12cm in lesser, and 16— 20cm 

 in greater diameter), ovoid or subconical, laterally compressed, un- 

 branched ; rock hard, gray on weathered surfaces, drab in the in- 

 terior, black on fresh exposures, with rather high specific gravity; 

 organs of the armor horizontal ; rows of scars forming an angle 

 in either direction of 45°-5o°; leaf scars subrhombic, i5-2omm 

 wide, 7-9mm high; leaf bases hard and firm, rough on the exposed 

 ends; walls 2-4mm thick, light colored and contrasting with the leaf 

 bases, sometimes with a median ridge; reproductive organs few and 

 poorly preserved ; armor 2-4cm thick, joined to the axis by a clear 

 line; wood i5-2omm thick; outer zone 5mm thick, traversed by rays 

 or vessels ; inner zone consisting of two rings, the outer 5mm thick 

 with fine radiate structure showing medullary rays and woody wedges, 

 the inner 5-iomm thick of a less definite structure; medulla elliptical 

 in cross-section, lesser diameter 2-3cm, greater Scm, homogeneous. 



The two specimens Nos. 500.28 and 500.31, which I have brought 

 together here, have at first view very little to mark them or interest the 

 student, but while they differ essentially from all others in the col- 



