432 N. E. Stevens— Petrified Palms. 



times, and always in surroundings indicating the Pierre. From 

 at least one occurrence of these palm stems it was evident that 

 transportation for a long distance from the overlying Oligocene 

 was not possible. I hold them as certainly Cretaceous. 



The sections of palm wood cut by Wielaiid at the time 

 of his original publication were in 1920 turned over to 

 me for further study, and from them the accompanying 

 figures have been made. 



For convenience in comparison there is included in the 

 present paper a description of a species of palm wood 

 from the low^er portion of the Denver formation (Eocene). 

 The speciuien upon which this species is based forms 

 part of a large collection of Palmoxylon material obtained 

 by Dr. George L. Cannon of Denver, and with other repre- 

 sentative material from the same collection has been 

 presented by him to the Yale Museum. Dr. Cannon's 

 collection of petrified palm stems is the most notable thus 

 far brought together in Xorth America and deserves full 

 monographic treatment. The sections of the Denver 

 palm were prepared at the U. S. National Museum 

 through the courtesy of Dr. George P. Merrill. 



Pahnoxijlon clieijennense Wieland 



The palm stems of the Cheyenne have not been traced 

 back to material in situ thus far. So that only the eroded 

 stem centers are at hand. These are found as more or 

 less spindle-shaped forms several feet in length by four 

 or five inches in diameter. Being calcified, the sections 

 must be ground with some care. 



Structure. — Although the preservation is so excellent, 

 and the sections carefully made, the wood of P. clieijen- 

 nense appears dense in cross section. This is due to the 

 large size and relatively compact arrangement of the 

 fibrovascular bundles (cf. figs. 1 and 2), to the presence 

 of numerous bast strands between these bundles, and to 

 the absence of large intercellular spaces among the cells 

 of the fundamental tissue. 



The cells of the fundamental tissue present no unusual 

 features. They are variable in size and shape, and are 

 closely packed, with few or no intercellular spaces. No 

 pitting is evident in their walls, and there are no specially 

 thickened or differentiated cells. The auxiliary scleren- 

 chyma bundles, rather regularly scattered among the 



