of the Middle Atlantic Coast Eocene. 373 



zone 17, embraces so far as can be determined about 45 feet at 

 the top of the series. It contains among other Gulf forms, Fxtsus 

 (Levifusus) trabeatus, Solemya petricoloides, Corbula nasuta, 

 Corbula oniscus, Venericardia planicosta, Nucida magnifica 

 and Ostrea sellaformis, the latter species increasing in number 

 toward southern Virginia and affording thick beds on the 

 Pamunkey and James rivers. At the same time the common 

 forms of the Aquia Creek stage are wanting. Although not pos- 

 sessing the number of distinctive species found in the preceding 

 divisions, the Woodstock stage is nevertheless in all probability 

 the representative of the Claiborne of the Gulf, showing a closer 

 parallelism, perhaps, with the beds beneath the fossiliferous 

 sands than with the upper horizon of that division. 



Between the fossiliferous beds carrying the faunas of 

 the two stages are very nearly 125 feet of strata in which 

 few fossils have been found outside of Venericardia planicosta. 

 Many of the beds seem to be wholly barren of organic remains, 

 while in others only a few indeterminable casts appear. No 

 satisfactory paleontological data for correlation are therefore 

 afforded by these deposits. 



If now the Aquia Creek fauna should be held to be suffi- 

 ciently similar to the Bells Landing fauna of the Gulf to 

 warrant its restriction to that sub-stage (middle Lignitic) ; and 

 the Ostrea sellwformis bed of the Woodstock stage, the exact 

 equivalent of the Ostrea sellwformis zone of the Claiborne 

 (middle Claiborne), then we find the 600 feet between those 

 horizons in central Alabama represented by only 125 feet in 

 the middle Atlantic slope and perhaps by considerably less. 

 The representatives of the Woods Bluff and Hatchetigbee 

 stages of the Lignitic together with the Buhrstone and lower 

 portion of the Claiborne would thus be here included. The 

 upper beds of the Woodstock stage might then be regarded per- 

 haps as the equivalent of the upper Claiborne, while the 60 feet 

 below the Aquia Creek fossiliferous beds would approximately 

 represent the earlier portions of the Lignitic. As these lower 

 beds are much more glauconitic than the beds above the Aquia 

 Creek stage, they doubtless accumulated more slowly. 



It is apparent, however, that the sequence of organic remains 

 in the middle Atlantic coast Eocene does not afford the neces- 

 sary data for a detailed parallelism of the subdivisions of that 

 area with the Gulf stages. It seems altogether probable that 

 the Pamunkey formation is the equivalent in a broad way only 

 of the lower and middle divisions of the Eocene of the 

 Gulf, and may even represent portions of the upper division as 

 well. Regarding the latter reference there is little paleontol- 

 ogical evidence, but undoubtedly less change in faunal devel- 

 opment would be produced under the stable conditions that 

 prevailed in Eocene time in the middle Atlantic slope than in 

 the Gulf, so that the more highly developed fauna of the 



