FLORA OF THE TRINITY FORMATION. 331 



In the section which occupies pages 188 and 189 he places the 

 Trinity division in the Upper Jurassic, although in Chapters XI and 

 XII he had called it Lower Cretaceous and included it in the Comanche 

 series. 



This latter view seems to have been his maturer judgment, for in 

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

 lished a year later, he does this systematically and has since consistently 

 adhered to this classification. 



Very little additional information relative to the Trinit}' formation 

 is given in Mr. Hill's contribution to the First Annual Report of the 

 Geological Survey of Texas, ** which bears date 1890, and the section 

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



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

 on December 30, 1890,'' and published 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 Trinity overlying the basal sands and consisting of alternating beds 

 which he calls the Glen Rose beds. These are quite full^y described 

 and appear to have been previously included in his Fredericksburg 

 division. In concluding his account of them he says: 



The different lithologic and stratigraphic features of the Glen Rose alternating 

 beds, their position beneath the Fredericksburg division (separated in the north by 

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

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

 position, although they are separated 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 mistakenly considered Quaternary in age." 



"A preliminary annotated check list of the Cretaceous invertebrate fossils of Texas, etc., by Robert T. 

 Hill: Bulletin Geol. Survey, Texas, No. 4, Austin, 1889, p. xiv. 



''A brief description of the Cretaceous rocks of Texas and their economic uses, by Robert T. Hill; 

 First Ann. Rep. Geol. Surv., Texas, Austin, 1890, pp. 10.5-141. 



'■The Comanche series of the Texas-Arkansas region, by Robert T. Hill; Bull. Geol. Soc. Am., Vol. II, 

 May 5, 1891, pp. 503-528. 



