306 Gardner — Relation of the Late Tertiary Faunas 



in a general way, it has marked for geological epochs the 

 southernmost extension of the northern forms and the north- 

 ernmost extension of the southern. 



The tout ensemble of the late Tertiary faunas is very 

 similar to that of the existing fauna of the east coast of the 



Fig. I. 



Fig. 1. Map showing areal distribution of Late Tertiary of Virginia and 

 North Carolina. 



Horizontal lines = Yorktown Formation. 

 Vertical lines =■ Duplin ' ' 



Solid block = Waccamaw ' ' 



United States. The Pelecypoda, although much more prolific 

 in individuals, are exceeded in the number of species and sub- 

 species by the Gastropoda, the former numbering only 363, or 

 45*2 per cent of the whole, while the latter number 430, or 



