NEW FOSSIL IMOLLUSKS FROM THE MIOCENE OF 

 VIRGINIA AND NORTH CAROLINA, WITH A BRIEF 

 OUTLINE OF THE DIVISIONS OF THE CHESAPEAKE 

 GROUP 



By We>;dell C. Mansfield 

 Of the United States Geological Survey 



The purpose of this paper is to briefly outline the different divisions 

 of the Chesapeake group of the Miocene epoch in Virginia and to 

 describe and ilkistrate seven new species and five new subspecies of 

 mollusks occurring in some part of this group. 



I wish to express my sincere thanks to the officials of the United 

 States National Museum for the facilities offered by this institution 

 in the use of former collections. The types of the described mollusks 

 are deposited in the United States National Museum. 



DIVISIONS OF THE CHESAPEAKE GROUP 



Inasmuch as a more complete discussion of the divisions of the 

 Chesapeake group is to be published under the heading " Summary 

 of the Miocene stratigraphy of Virginia based upon the study of the 

 fauna " in a volume forming a number of the George Washington 

 University Bulletin, it is undesirable to give here more than a brief 

 outline. 



The following divisions are recognized : 



Chesapeake j,TOup 



Torktown formation < 



Zone 2, or Turritella alti- f "^P^,^ P''^''^ 

 costata zone muldlepart 



[ lower part 



. Zone 1, or Pecten clintonius zone 



Zone 2, or Crassatellites meridio.'ialis 

 zone 



St. Marys formation s r, ^ t. >,• • 



Zone 1, or BuUiopsis quadrata 



I Stratum A 



zone 



Choptank formation 

 i Calvert formation 



No. 2759.-PROCEEDINGS U. S. National Museum, Vol. 74, Art. 14. 



5926 — 28 



