326 MESOZOIC FLORAS OF UNITED STATES. 



and the Fuson formation. This last immediately imderlies the heavy 

 quarry sandstone which he includes in the Dakota formation. 



On page 527 Mr. Darton mentions his discovery of saurian bones "in 

 the middle of the Lakota formation, or alwut 90 feet above the uncon- 

 formity of the Unkpapa sandstone, which is approximately the horizon 

 that has yielded cycads in the region between Edgemont and Minne- 

 kahta, near Blafckhawk, and elsewhere about the hills." Commenting 

 on this fact, he says: "If it were not for the evidence of the flora these 

 bones would be regarded as late Jurassic in age. They will soon be 

 described by Dr. F. A. Lucas, of the United States National Museum." 

 They have now been described and the species is named Stegosaurus 

 Marshi." Mr. Lucas makes no reference to the age except in the title, 

 but if the dermal spine found by Mr. J. B. Hatcher in the Triceratops 

 beds belongs to this species it ranges entirely through the Cretaceous. 

 Mr. Darton's remark, therefore, quoted above, is scarcely justified in 

 the present state of knowledge. 



fIjORa of the trinity formation. 



Petrified wood is always the first form in which vegetable remains 

 are observed in any country where it occurs, the discovery of the impres- 

 sions of leaves, stems, fruits, and flowers being reserved for the close 

 observations of the geologist and paleontologist when they chance to 

 visit the region. It was so in Texas, and the record of the observation 

 of silicified wood dates back at least to 1841. Mr. William Kennedy, in 

 his work on Texas '' of that date, mentions this fact in the following terms : 



In the middle, and northern sections of the district lying between the Trinity 

 and Neches rivers, great numbers of petrified post oak lie imbedded in the soil, 

 some in a horizontal position, but the larger portion nearly upright, with an inclina- 

 tion toward the north. They are extremely hard, giving fii-e to steel; generally 

 of light-gray or reddish-brown color, and present distinctly the form of the trunk 

 of the post oak, even to the knots. 



There is, of course, no certainty that the fossil wood here referred to 

 belonged to the Trinity formation, as it is found at several horizons in 



"A new dinosaur, S^e^osawrus Marshi, horn the Lower Cretaceous of South Dakota, by Frederic A.Lucas: 

 Proc. U. S. Nat. Mus., Vol. XXIII, 1901, pp. 591-592, pi. xxiii, xxiv. 



''Texas: The Rise, Progress, and Prospects of the Republic of Texas, in two volumes, by William Ken- 

 nedy, esq., London, 1841, Vol. I, pp. 119-120. 



