FLORA OF THE TIJTMTY FORMATION. 331 



In tho section whicli occupies pages 188 and ISO he places the 

 Trinity division in tiic I'ppcr .Inrassic, although in Cliaptei's XI and 

 XII he had called it Lower Civtaceous and included it in th(> Comanche 

 series. 



This laltcM- view seems to have been his maturei' Judgment, foi' in 

 the section which he introduces into his Aiuiotated Check List," pub- 

 lished a yeai- latei, he does this systematically and has since consistently 

 adhered to this classiHcation. 



Very little additional information relative to the Trinit}' formation 

 is given in Mr. Hill's conti'ihution to the I'irst Aimual Report of the 

 Geological Survey of Texas,'' which hears date ISDO, and the section 

 on jKiges 132-133 conforms to the one last mentioned. 



In a paper read by Mr. Hill before the (ieological Society of America 

 on December 30, 1890,' and pul)lished in its bulletin, several important 

 new features are introduced. The one which most concerns the present 

 discussion is the recognition by Mr. Hill of an upper subdivision of 

 the Ti'inity overlying the basal sands and consisting of alternating l)eds 

 which he calls the Glen Rose l)eds. These are quite fully described 

 and appear to have been previously included in his Fredericksburg 

 division. In concluding his account of them he says: 



Till' (rillcriMit iithoiogic and stratigni|)hic features of the Glen Rose alternating 

 beds, their ])osition beneath tlie Fredericksburg division (separated in the nortli by 

 a sandy, Httt)ral terrane), and the entire absence of the great characteristic fauna 

 of the hitherto recognized Fredericksburg division, entitle these beds to a distinct 

 position, iiitliough tiiev are se|)arated by no structural unconformity. 



Another new feature added in this paper is the Paluxy sands, which 

 he here places at the base of the Fredericksburg division and describes 

 on pages 510-511, and remarks that "no fossils have been found in 

 the Paluxy sands save silicified wood, which occurs in great abundance 

 and has been mistakenl}' considered Quaternary in age." 



" A prcliiiiinarv annotated check list of the Cretaceous invertphrate fossils of Texas, etc., Iiy luilicrl T. 

 Hill: Bulletin (Icol. Survey, Texas, Xo. 4, .\ustin, 18S0, p. xiv. 



''A brief description of the Cretaceous rocks of Texas iuid their economic uses, hy Robert '1'. Uill: 

 First Ann. Rep. (ieol. Surv., Texas, Austin, 1890, pp. 1().t-UI. 



<■ The Conumche .series of the Texas-Arkansas region, by Robert 'I'. Hill; 15ull. (ieol. Soc. Aiu., \'(>1. II, 

 May 5, 1891, pp. .503-528. 



