262 T. W. STANTON DAKOTA SANDSTONE PROBLEMS 



lion, Fort Worth limestone, and Denison formation. The time equiva- 

 lents of all of these formations are probably represented in the Cheyenne 

 sandstone and Kiowa shale of southern Kansas, but in the Mentor of 

 central Kansas apparently only the Denison formation, and possibly only 

 its upper part, is represented. Above the Denison formation lies the 

 Woodbine sand, which is considered the approximate equivalent of the 

 Dakota, the Eagle Ford clay, which represents the Benton sequence of 

 the north interior region, and the Austin chalk, which is correlated with 

 the Niobrara. 



The Woodbine sand in its upper part contains a considerable marine 

 fauna which has not yet been fully described. Cragin 9 lists the following 

 species : 



Ostrea soleniscus Meek. 



Ostrea carica Cragin. 



Exogyra ferox Cragin. 



Exogyra eolumbella Meek. 



Pteria salinensis White. 



Ayuilcria cumminsi White. 



Modiolus filisculptus Cragin. 



Area galliennei var. tramitensis Cragin. 



Trigonarca siouxensis Meek and Hayden. 



Cytherea leveretti Cragin. 



Turritella coalvillensis Meek. 



Turritella renauxlana d'Orbigny. 



Cerithium tramitensis Cragin. 



Cerithium interUneatum Cragin. 



Neritopsis tramitensis Cragin. 



RELATIONSHIPS OF THE FAUNA 



There are a number of undescribed species in this fauna, including two 

 or more species of Acanthoceras in the collections of the United States 

 Geological Survey. The relationships which this fauna suggest to me are 

 on the one hand with the Dakota fauna of eastern Nebraska and north 

 central Kansas and on the other with the lowest Mancos fauna of central 

 New Mexico and southern Utah. The geologists of the Texas Bureau of 

 Economic Geology and Technology have assigned the Woodbine sand to 

 the Washita group and tentatively correlated it with the Buda limestone 

 of central and southern Texas, but the evidence on which this classifica- 

 tion and correlation were based has not been published. There is cer- 

 tainly no direct paleontologic evidence that would justify the correlation. 



!l K. W. Cragin : Contributions to the invertebrate paleontology of Texas. Geological 

 Survey of Texas, 4th Ann. Kept., 1893. 



