FORMER CONTINUITY OF CRETACEOUS STRATA. 523 



topographic sheets of the United States Geological Survey, or has seen the 

 reranantal buttes of the Cretaceous, red bed. Carboniferous and Cambrian 

 formations standing as mute witnesses above the older rocks will see most 

 undisputably recorded their deep burial beneath the Cretaceous seas. 



The Age of the Comanche Series. 



To me, the age of the Comanche series has and ever will be a question of 

 secondary consideration to its stratigraphic and faunal definition. I cannot 

 refrain, however, from calling attention to a few data which must be of in- 

 terest to those who insist upon trans-oceanic correlation. 



It being admitted by all students that the Dakota sands, which rest uncon- 

 formably upon the Denison beds in Texas, are the base of the upper Creta- 

 ceous and show remarkable specific identity with the upper Cretaceous beds 

 of Europe, the stratigraphic position of the Comanche series as a lower for- 

 mation cannot be doubted. In ray check-list of the invertebrate fossils of 

 the Texas Cretaceous, I have endeavored to give the history and stratigraphic 

 range of each known species. Since that work was prepared I have made 

 many additions and a few corrections. If the paleontologist will compare 

 the species and faunas enumerated in that list with those of Europe, he will 

 soon come to the conclusion that there is no specific similarity in the beds 

 below the Exogyra texana clays, and that there are the most radical differ- 

 ences in stratigraphic occurrence. He will find that in the lower half of the 

 Comanche series (the Glen Rose and Trinity beds) there is not a single 

 species of characteristic Cretaceous age, and that while there are no crite- 

 rional forms, such as ammonitidse, echinodermata, etc., any of the genera 

 can be as well referred to the Jurassic as to the Cretaceous. 



In the Fredericksburg or Comanche Peak division, the lowest occurring 

 and most abundant species, the Exogyra texana {E. matheroniana), which 

 occurs here only in the very lowest beds of the undoubted lower Cretaceous, 

 are characteristic of the very uppermost member of the European Cretaceous, 

 the Senonian. This is the only species of the Comanche Peak division, how- 

 ever, which is known positively to occur in Europe. The two Ammonites 

 (^Ammonites pedernalis, Roemer, and Schloenbachia peruvianus, von Buch) 

 are unknown in Europe, and the first is of a Triassic ceratitic type, while 

 the other is found only in South America and Benguela land, Africa, in 

 beds of undetermined age. The echinodermata have been pronounced by 

 Professor Louis Agassiz to be of Neocomian type, while the variety of Gry- 

 phcea is a Jurassic type in Europe. Again, in the Caprina limestone occurs 

 the only Hippurite in all the north American Cretaceous, while in Europe 

 the genus ranges through the middle and upper divisions. In the Washita 

 division, hoAvever, there are many species of undoubted European similarity 



