H. T. Hill — Texas Section of American Cretaceous. 299 



sediments between the well defined upper and lower deep 

 marine groups and they constitute the middle division of the 

 Cretaceous. I therefore present their fauna as a whole without 

 detailed attempt at separation. 



Ostrea anomiaformis Roera. 



Ostrea congesta Con. ? 



Ostrea bellr/plicata Shum. 



Ostrea Blackii White. 

 Exogyra columbella Meek. 

 Barbatia, sp. no v. 



Cucullcea millestriata Shum. 

 Nucula bellastriata Shum. 

 Nucula Hoydeni Shum. 

 Nucula serrata Shum. 



Lucina sublenticularis Shum. 



Cyprimera crassa Meek. 



Grassatella parvula Shum. 

 Diane (" Cytherea") lamure?isis, 

 Tapes Hilgardi Shum. 



Venilia (Cyprina) Laphami 

 Shum. 



Venus sublamellosus Shum. 



Corbida. Tuomeyi Shum. 



Gervilia Mudgeana. White. 



Gerviliga regaria Shum. 



Aguillaria? Cwnminsi White. 

 Avicula irridescens Roem. 

 Inoceramus capulus Shum. 



Inoceramus mytilopsis Con. 

 Inoceramus mytiloides Mant. 

 Nearea alwformis Shum. 

 In ocera m us problematieus 



Schlot. 

 Cylichna minuscula Shum. 

 Neritopsis biangulatus Shum. 

 Tornatella texana Shum. 

 Ringicula acutispira Shum. 

 Bingiada subpellucida Shum. 

 Scalar ia lamarensis Shum. 

 Cerithium, sp. no v. 

 Baculites gracilis Shum. 

 Scaphites semicostatns Roem. 

 Scaphites texanus Roem. 

 Ancyloceras annulatum Shum. 

 Ammonites percarinatus M. & 



H. 

 A. Graysonensis Shum. 

 A. inaequiplicatus. 

 A. Meelcianus Shum. 

 A. Swallovii Shum. 

 Fish remains. 

 Dicotyledonous leaves. 



The Lower Division of the Texas Cretaceous. 



The harder limestones, seen underneath the Lower Cross 

 Timber beds at Port Worth and Denison and the shales at 

 Austin, and forming the face and plateau of the escarpment, 

 are the undoubted top of the Comanche* series of my former 

 paper. This great formation, which constitutes the face of the 

 escarpment and the great plateau at its top, covers or once 

 covered the whole of the central region as far west as the 

 Rocky Mountain region. This group of strata embraces thou- 

 sands of feet of deep marine sediments and extends over an 

 immense area in Texas. At San Marcos, New Braunfels, 

 Austin, and many other places throughout the central region, 

 the strata are beautifully shown. Four miles northwest of the 

 latter city the banks of the Colorado afford a vertical exposure 

 of over 700 feet, and yet these are only the topmost strata of 



*The name Comanche is given to this series owing to the fact that it was at 

 the town of that name that I first studied it. and that the Central Denuded 

 Region of Texas, where the formation is found, was the home of the Comanche 

 Indians. 



