32(; ilESOZOIC FLORAS OF rXITED STATES. 



and the Fusoii formal ion. This last immediately underlies the heavy 

 (luarrv sandstone which he includes in the Dakota formation. 



On page 527 Mr. Dailon mentions his discovery of saurian hones "in 

 the middle of the Lakota foi-mation. or al)Out 90 feet above the uncon- 

 formity of the Unkpapa sandstone, which is approximately the horizon 

 that has yielded cycads in the region between p]dgemonl and Minne- 

 kahta, near Blackhawk, and (Msewhere al)out tlic liills." Commenting 

 on this fact, he says: "If it were not for tlie cvid('nc(> of the flora these 

 bones would be regarded as late Jiu'assic in age. They will soon be 

 described by Dr. F. A. Lucas, of the I'^nited States National Museum." 

 They have now been described and the species is named Stcgomurus 

 Mar.-^hi." Mr. Lucas makes no reference to the age except in the title, 

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

 beds belongs to this species it ranges entirely tlirough tlie Cretaceous. 

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

 the present state of knowledge. 



FliORA OF VUK TRINITY FORMATION. 



Petrified wood is always the first form in which vegeta]:)le remains 

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

 sions of leaves, stems, fruits, and flowers l)eing 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 : 



ill the middle and northern sections of the district lying between the Trinity 

 and Neches rivers, great numbers of ])etrified post oak he imbedded in tlie soil, 

 some in a horizontal position, l)ut the larger portion nearly upright, with an inclina- 

 tion toward the north. They are extremely hard, giving fu-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 dinos&ur, Stegiixniiiiix .Uarshi, from tlie Lower Cretaceous of South Dakota, 1)V Frederic A. IjUcius; 

 Proc. U. S. Nat. Mus., Vol. XXIll, lifOl, pp. 5i»l-.i92, pi. x.xiii, xxiv. 



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

 nedy, esq., London, 1S41, Vol. I, pp. 119-120. 



