272 W. Cross — Denver Tertiary Formation. 



quartz in strata nearest the mountains shows that it could not 

 have come from that direction. 



c. The Fossil Flora. 



The Golden fossil flora has been fully described and repeat- 

 edly discussed in its bearing upon the age of the Laramie for- 

 mation. Inasmuch, however, as some of the plants came from 

 acknowledged Laramie and others from the Denver strata of 

 Table Mountain, while all have been uniformly referred to the 

 former group, through ignorance of the facts here presented, 

 it seems plain that this fossil evidence cannot be used as a 

 whole in discussing the age either of the Laramie or of the 

 Denver beds. An examination as to the distribution of species 

 in view of new evidence is naturally a matter for the palgeobot- 

 anist to undertake, but it seems advisable to call attention in 

 this place to certain facts concerning the past discussions of 

 these fossil plants and to their present condition. 



The Golden flora as described by Lesquereux. — By far the 

 greater number of the plant remains from Golden have been 

 described by Prof. Leo Lesquereux, originally in the annual 

 reports of the Hayden Survey and afterwards in revised form 

 in the previously cited monograph, " The Tertiary Flora." A 

 few additional species were described in the later monograph, 

 "The Cretaceous and Tertiary Floras." In the former work 

 95 species from Golden are described, and in the latter 8 others, 

 making a total of 103 species and varieties from this locality. 



In the following discussion two varieties of Ficus planicos- 

 tata Lx , are omitted, as is likewise the Cycad species, Zamios- 

 trobus mirabilis Lx., the single specimen of which is stated by 

 Lesquereux to have been " found by Dr. F. V. Hayden on the 

 surface soil without connection to any stratum of rock."* 

 Deducting these three there remain just 100 species of fossil 

 plants to be considered, hence many of the numbers to be given 

 express percentages of the Golden fossil flora as described by 

 Lesquereux. 



An examination of the monographs cited shows that 81 spe- 

 cies were originally described by Lesquereux ; 59 species are 

 known in the United States only at Golden, — 52 of these being 

 new species. 



As to the exact geological horizons of the species ; three per cent 

 only are definitely stated, under the heading " Habitat," to come 

 from the known coal-measure sandstones, while 13 per cent are 

 said to come from Table Mountain. Through incidental state- 

 ments as to the horizon it seems plain that 9 per cent came from the 

 acknowledged Laramie and 16 per cent from Table Mountain 



* "Tertiary Flora, "p. tl>. 



