THE OLDER MESOZOIC OF ARIZONA. 15 



bones was the richest m this respect, and the greater part of Mr. Brown's 

 collection was made within a mile or more of the original localit}'. 



It will of course be impossible for me to give any adequate account 

 in this place of Mr. Brown's collection of Triassic bones. Suffice it to 

 say that he made an extensive collection, consisting to a considerable 

 extent of well-recognized bones, some of them entire, others capal^le 

 of having the separated pai'ts brought together, but others, of course, 

 as in the case of Triassic bones the world over, more or less fragmentary. 

 They represent chiefly the Belodont, Heterodontosuchus ganei Lucas, 

 mentioned in the first paper, page 323, but teeth and other parts were 

 found that probably belong to ancestral dinosaurs, while one very large 

 scute belongs to the genus Labyrinthodon. The collection was shipped 

 to the National Museum at Washington. It has been unpacked under 

 the direction of Mr. F. A. Lucas, in whose hands it will doubtless be 

 carefully worked up and the results duly published." 



I am very glad to be able to record the success of this expedition 

 from the standpoint of vertebrate paleontology, because from the stand- 

 point of fossil plants my anticipations were laot realized. In a region 

 which contains almost everywhere such an enormous quantity of silicified 

 wood and which consists so largely of sedimentary and definitely strati- 

 fied rocks it was reasonable to suppose that there would be found occa- 

 sional beds at least in which impressions of the foliage, fruit, and flowers 

 would be preserved. But the search was almost wholly without success, 

 and the conclusion was reached that for one reason or another the con- 

 ditions for the preservation of the parts of plants which are most essen- 

 tial in the determination of the flora were absent from this entire region. 



The explanation of the absence of plant impressions of the more deli- 

 cate kind is probably to be found mainly in the great abundance of gypsum 

 that prevails throughout all these beds, which, as is well known, is almost 

 fatal to the preservation of organic remains. But for it no doubt the 

 vertebrate remains would be much more abundant and complete, and it 

 is only the silicified wood that seems to escape its influence. This latter, 

 however, is mainly deposited in beds of sand, coarse gravel, or conglomer- 

 ate, which, in themselves, are unfavorable to plant impressions. 



f'A preliminary report was published by him in Science, N. S., Vol. XIV, September 6, 1901, p. 376. 



