FOSSIL CYCADEAN TRUNKS FROM WYOMING 273 



on the weathered surfaces, dark within with w^hite stripes, of medium 

 specific gravity; organs of the armor ascending, especially above the 

 middle, towards the summit, as seen on the fractured surfaces, curving 

 first upward and then gracefully outward in continuation of the clearly 

 marked strands from the interior of the axis ; leaf scars subelliptical or 

 subrhombic, 1 2-1 5mm wide, 5— 6mm high; leaf bases hard, dark 

 and porous; walls 3-5mm thick, hard and smooth, light colored or 

 nearly white; reproductive organs few and obscure; armor 3-5cm 

 thick, irregularly joined to the axis ; woody zone 2cm thick, undif- 

 ferentiated, medulla 2-3cm in diameter, black, striped and blotched 

 with white flinty patches. 



This species includes the specimens numbered 500.42, 500.46, 

 500.59, 500.71, and 500.75, but they all probably belong to the same 

 trunk. No. 500.46 matches No. 500.42 and No. 500.75 matches No. 

 500.46 by a narrow facet, with the loss of intervening chips. No. 

 500.71 has exactly the same markings as No. 500.42 on the side op- 

 posite No. 500.46. These markings are too definite and peculiar to 

 recur, and amount to a proof of identity, although a thin plate between 

 has disappeared. No. 500.59 is evidently the downward continuation 

 of No. 500.42. On one side there is almost complete continuity, but 

 a large triangular piece is wanting on the other side. 



The weights of the pieces are as follows : 



No. 500.42, 1.53 kilograms. 

 " 500.46, 0.57 

 " 500.59, I. II " 



" 500.71, 0.28 " 

 '' 500-75' 0-70 



After all are put together we still probably have less than half the 

 original trunk. 



CYCADELLA EXOGENA n. sp. 



Trunks small or of medium size (i2-2ocm high, 8-2ocm in diam- 

 eter), ellipsoidal, somewhat compressed laterally or (in one specimen) 

 vertically, unbranched ; rock hard and fine-grained, light colored on 

 the weathered surfaces, dark within, variegated with brown or white 

 stripes or spots, of medium specific gravity ; organs of the armor hori- 

 zontal ; rows of scars making an angle of 50° with the axis in both 

 directions (traceable only in one specimen) ; leaf scars subrhombic, 

 i2-2omm wide, 6-9mm high; leaf bases hard, fine in structure, punc- 

 tate or porous; walls i-3mm thick, soft-sandy, and more or less de- 

 cayed, light colored, sunken between the leaf bases, striate or wrinkled, 

 sometimes with a median line or commissure; reproductive organs 



