Weno and Pawpaw Formations 43 



and a pair of twinned ventro-marginal ones, as indicated by Pervinquiere? 

 If the latter, there is no Duck Creek species known to me that approaches 

 it as closely as do several Upper Washita species. For only above the base 

 of the Weno do we begin to find fairly large (6-12 inches) coarse straight 

 ribbed square coiled ammonites with an umbilical and a twinned marginal 

 tubercle ; this is the commonest and most characteristic Weno calcite spe- 

 cies, and it abounds in slightly smaller size in the nacreous ironstone Weno 

 fauna (Plate 3, figure 11). In the Pawpaw clay the same type is abun- 

 dant as small pyritic casts (M. worthense, Plate 1, figures 6-10, 18-19, 26), 

 having extremely short coarse ribs with very prominent twinned marginal 

 tubercles and a narrow square volution. Again in the Mainstreet lime 

 stone the common calcite species has lower, somewhat sigmoid ribs with 

 twinned marginal tubercles and a rectangular section. Are any of these 

 inflata? If the Vraconian is to be placed in the Weno, which seems pos- 

 sible, the whole Cenomanian will have to lie between the Pawpaw and the 

 base of the Eagleford shales, which is generally claimed to be the base of 

 the Turonian. Again a Duck Creek species similar to Schloenbachia elob- 

 iensis has been noted ; but a comparison of Szajnocha's figures and descrip- 

 tion indicate that this species is different from his ; its section is much lower, 

 and the shell bears spiral circlets which form regular radial rows contain- 

 ing numerous imbricated lips, while in the Texas species (known only as 

 internal casts) there are radial rows of only a few rounded tubercles; in 

 addition, the stratigraphic data given by Szajnocha are inadequate for cor- 

 relation with the Texas strata. 



A comparison of the Duck Creek limonite fauna with the African Vra- 

 conian yields only slight results. On the theory that the Pawpaw is Vra- 

 conian, the Duck Creek could scarcely be placed earlier than the Albian, 

 since the Glenrose is with some certainty assigned to the Aptian. But Al- 

 bian species' are not apparent in the Duck Creek limonite fauna, whose am- 

 monites are preponderantly small species of Schloenbachia and Hamites, 

 with scattering Scaphites sp. aff. aequalis. Desmoceras, etc. Hoplites and 

 other abundant Albian genera are so far unknown. The fauna on the other 

 hand is predominantly Vraconian. This Vraconian aspect appears to end 

 with the Duck Creek limestone oj marl, since with the next limonite fauna, 

 that of the Denton marl, there seem to be some species with Cenomanian 

 affinities. Comparison of the Texas Washita faunae with those of Western 

 Europe, examples of which are before me, shows much less resemblance 

 than with the Northern African fauna. Common European species, as 

 Douvilleiceras mammilare, Schloenbachia varians, S. mantelli, and Holas- 

 ter subglobosus have no representatives in the Texas material so far 

 known. On the other hand, the Mainstreet, Grayson and Buda faunae are 



listed among other places in: Tomitch: Contributions a la Connaissance de 1'etage 

 Albien dans le Sud-Est de la France. Le Mans, 1918. 



