44 University of Texas Bulletin 



of a higher Cenomanian type, containing for example Codiopsis sp. aff. 

 doma, Tissotia spp., and Acanthoceras spp. ; and Berry states 1 that the Da- 

 kota (Woodbine?) flora is of Turonian age. 



On the whole then the Pawpaw fauna is placed provisionally as Ceno- 

 manian with much uncertainty as to its exact position. This question will 

 be settled when the rich ammonite faunae of the Lower Washita are crit- 

 ically studied. The Texas Comanchean sea was transgressive or at least 

 not regressive for a long period so that the relatively stationary shallow- 

 water conditions may not have encouraged a rapid evolution of these am- 

 monites; whatever the cause, they present notable similarities from the 

 earliest to the latest pyrite faunae known in the Texas Comanchean. On 

 the theory of persistent and nearly stationary species from Vraconian to 

 Cenomanian time some nearly similar species should be much extended ver- 

 tically in the Lower Washita sediments; further study of the proper ma- 

 rine facies of each stratigraphical level should reveal these and by filling in 

 the great gaps in our paleontological knowledge give a fairly complete 

 faunal succession. It is hoped that information on the extent of the various 

 marine facies in the Texas Comanchean formations will contribute to this 

 result. 







PALEONTOLOGY 



The rich Weno and Pawpaw faunae initiate a new group of species after 

 the considerable paleontological break which occurs at the top of the Den- 

 ton marl. The Werio formation, besides containing characteristic ammon- 

 ites, is notable in its marl facies for an exuberant echinoid fauna, and in 

 its shale facies for a great abundance and variety of distinctive cephalo- 

 pods, pelecypods and gastropods preserved with the original nacreous shell. 

 Certain elements of this nacreous fauna forcibly remind one of the Eocene 

 faunae, with which they have many genera in common. The fossils are 

 perfectly preserved, often with iridescent luster, and the original shell 

 shows the minutest details : in pelecypods, prodissoconch and other embry- 

 onic stages, ligament, and usually the finest features of dentition and ex- 

 ternal ornamentation ; in the cephalopods, the original pearly or iridescent 

 shell, and beneath this, finely preserved sutures etched into the ironstone 

 interior. 



The Pawpaw formation on the other hand contains a diverse and char- 

 acteristic assemblage of small pyritic ammonites, echinoids, pelecypods, 



iBerry: U. S. G. S., Prof. Paper 84, pp. 71, 128. 



