N. E. Stevens— Pefyifird Pahu. 



439 



Description of Species. 

 Palmoxylon cheyenneuse Wieland. 



Locality, — Pierre, Upper Cretaceous, near the Cheyenne Eiver soutli of 

 mouth of Battle Creek, Soutli Dakota. 



Type in Yale Museum. 



Fibrovascular bundles more numerous near the peri- 

 phery of the stem (about 35 per. sq. cm.) than inter- 

 nally (about 20 per sq. cm.), about 1 mm. in shortest 

 diameter by 1 to 1.5 in longest diameter, somewhat varia- 

 ble in size and shape, chiefly regular in outline. '^Pos- 

 terior sclerenchymous arch" present. Auxiliary scleren- 

 cliyma bundles numerous. Fundamental tissue of stem 

 without intercellular spaces or conspicuously thickened 



Fig. 11. — Pahnoxylon cannoni, outline showing relative size and arrange- 

 ment of the fibrovascular bundles of the stem. X 5. 



or pitted cells. The bast portion of the fibrovascular 

 bundles much larger than the vascular portion. 



The Denver Specimen. 



The .palm wood here selected for comparison w^ith 

 P. cheyennense occurs as a silicified black mass from near 

 the base of a large stem. In general appearance this 

 black and dense specimen suggests some meteorite of a 

 hundred or more pounds. The structure appears in 

 remarkable detail, only the phloem (which indeed may 

 have been destroyed before silicification) failing of pre- 

 servation. 



In contrast to P. clieyennense the wood of the Denver 

 specimen has the fibrovascular bundles rather widely 

 separated, {fi^. 11) only about ten per sq. cm. Typical 

 longitudinal bundles (fig. 12) measure from .8 to 1. mm. 

 by .9 to 1. mm. in diameter and contain characteristically 

 two large thick walled vessels, usually from .166 to .100 

 mm. in diameter. The sclerenchyma portion is rounded 



