4 Bulletin io 298 



The Tertiary and Pleistocene Foraminifera 



OF THE Middle Atlantic Slope. 



Introduction. 



The material investigated from the Eocene marl beds of the 

 Pamunkey river and Woodstock, Virginia, by the author, led to 

 the discovery of twenty-three different species of Foraminifera, 

 a classified list of which was published in Johns Hopkins Uni- 

 versity Circulars, vol. xv, 1895, P- 6, and again in Professor 

 W. B. Clark's report* on the Eocene Deposits of the Middle At- 

 lantic Slope in Delaware, Maryland, and Virginia. Later stud- 

 ies on Miocene deposits of several localities in Maryland and 

 Virginia and from the Pleistocene beds at Cornfield Harbor, 

 Maryland, resulted in the determination of a large number of 

 genera and species. The presence of so many microscopic organ- 

 isms proves how favorable were the conditions for their ex- 

 istance when these formations were being laid down. 



Historical Summary. 



The first description of Foraminifera from the Miocene of 

 Maryland appears to have been made bj^ Isaac Eea in his Con- 

 tributions to Geology. This work, published in 1833, contains 

 an article entitled "Description of six new Species of Fossil 

 Shells from the Tertiary of Maryland and New Jersey." which 

 was read before the American Philosophical Societj^, November 



I, 1833- 



One of the forms, Miliola marylandica, described on pages 

 215 and 216 , and figured on plate VI, fig. 227, represents 

 a smooth Milioline shell of three visible segments. This form 

 is undoubtedly identical with Miliolina seminulum (Linne), 

 and is so considered in this report. 



Prof. J. W. Bailey t in 1845 figures two Rotaline casts, one 

 from the greensand of Fort Washington, Maryland, the other 

 from Virginia, but the horizon from which they were obtain- 

 ed is unknown. As both Eocene and Cretaceous occur at 

 Fort Washington the specimen found there could belong to 

 either horizon, though it is more probable that it came from 

 the Eocene greensand. 



*Bul. U. S. Geol. Snrv., No. 141, pp. 91-92, 1896. 

 tAm. Jr. Sci., vol. xlviii, pp. 321-343, pi. iv, 1845. 



