Maryland Geological Survey 331 



The Magothy flora as developed in the Maryland area furnishes thirty- 

 six species that are common to the Dakota sandstone. It contains in 

 addition eight closely related species, and in their generic facies the two 

 floras are very similar. On the other hand, the Magothy flora shows no 

 points of contact with the floras of the Montana group of the Western 

 Interior, except such as are furnished by certain long-lived and long- 

 ranging species like Sequoia reichenbachi and Cunninghamites elegans, 

 which are without significance in close correlation. 



At least the middle and upper portions of the Upper Cretaceous are 

 present in the Mexican section. The faunas are most closely related to 

 those of Texas and possess in common with them an abundance of 

 rudistids and corals, elements which characterize the southern facies in 

 the western as well as in the eastern hemisphere. The Mexican faunas 

 contain, in addition, some of the species which have proved the most trust- 

 worthy horizon markers along the East Coast and Gulf and in the Western 

 Interior. Inoceramus labiatus, the type fossil of the Benton in this 

 country and of the Turonian in Europe, has been reported from Durango 

 near Juarez, Parras and Peyotes in Coahuila and Mazapil in Zacatecas. 

 The overlying strata in Coahuila which have been correlated with the 

 Emscher by Aguillera * are barren shales and limestones. Above these 

 are sandstones containing Exogyra ponderosa and Anomia argentaria. 

 The Exogyra costaia zone is even better defined than the ponderosa and 

 contains, in addition to the type species, Sphenodiscus lenticularis or 

 lobatus, Eutrephoceras dekayi and Crenella elegantula, a small bivalve 

 restricted in its known distribution to the Monmouth and the Fox Hills. 

 ISTo Cretaceous fauna above that of the costata zone has been differentiated 

 in Mexico. 



The correlation of the Maryland Upper Cretaceous faunas with those 

 of the Western Interior is much less direct than with those of the Gulf. 

 However, some of the cephalopods and Dentalia discovered a channel of 

 communication which was followed by a few bivalves. The fauna of the 



1 Aguillera, J. G., Guide des excursions de Xe Congres geologique interna- 

 tional, Mexico, (c) pp. 240-242. 



