30 MESOZOIC FLORAS OF UNITED STATES. 



remnant, he naturall}^ looked among Permian fossils for a figure with 

 which toxompare his specimen and does not seem to have looked further. 

 The Trias also yields ferns, and perhaps if he had examined figures of 

 Triassic ferns he would have found a figure of his plant. It is at least 

 certain that this defective piece of evidence is altogether without weight 

 in fixing the age of these beds. 



THE SEINARUMP FORMATION. . 



So far as concerns the vertebrate remains, sufficient has already 

 been said to show that all that were found came from a single phase of 

 the Shinarump formation, viz, the variegated marls. They occur in gen- 

 eral a little higher than the middle and 200 to 300 feet above the top of 

 the conglomerates. Very few other animal remains were found, but Mr. 

 Brown did collect a small number of shells and a few other invertebrates. 

 They are probably for the most part without diagnostic value, but as 

 they have not yet been determined it is impossible to discuss then- 

 significance. 



The only plant remains that I was able to discover, aside from 

 what belong properly to the fossil trunks, were certain forms occurring 

 in relief on the faces of sandstone rocks and shales. They consist of 

 stems having the Araucarian structure and showing the branches in 

 whorls, and of the raised casts of small twigs lying across one another 

 in all directions. No signs of the structure nor any carbonaceous 

 material accompanies these impressions, and they se^m to have resulted 

 from the etching away of the sandstone from between the twigs while 

 still in the beds, so that when subsequently exposed these markings 

 stand out very distinctly, though always somewhat worn. They prol3- 

 abh' all iDelong to the coniferous vegetation, but have very little value 

 in determining its exact nature. For convenience of reference in future 

 I shall name these forms Araucarites shinarumpensis. (See Pis. 1, 11.) 



No one who has not visited that region can form an adequate con- 

 ception of the inexhaustible quantity of silicified wood that occurs at all 

 horizons. The condition of things in the Petrified Forest has already been 

 set forth by others as well as myself." • It strongly attracted the attention 



"Twentieth Ann. Rep. U. S. Geol. Surr., Pt. II, 1900, pp. 324-332. Report on the Petrified Forest of 

 Arizona, by Lester F. Ward, Washington, 1900 (special publication of the Department of the Interior). The 

 Petrified Forest of Arizona, by Lester F. Ward: Smithsonian Report for 1899, Washington, 1901, pp. 289-307, 

 pi. i-iii (reprint of the last with three plates added). 



