414 PROCEEDINGS OF THE ACADEMY OF [1898. 



FOSSIL MOLLTJSKS AND DIATOMS FROM THE DISMAL SWAMP, 



VIRGINIA AND NORTH CAROLINA ; INDICATION OF 



THE GEOLOGICAL AGE OF THE DEPOSIT. 



BY LEWIS WOOLMAN. 



WITH NOTES ON THE DIATOMS. 



BY CHARLES S. BOYER. 



During the winter of 1897-98 the Dismal Swamp Canal was 

 widened and deepened, and the level of the central portion lowered so 

 as to dispense with the middle two of the four locks heretofore in use. 

 The work was done by the McManus Construction Company of 

 Philadelphia, steam rotary dredging machines being used in exca- 

 vating. These dredges brought up from the bottom, at points both 

 south and north of the Virginia-North Carolina boundary, large 

 numbers of marine mollusks. Through the appreciative interest in 

 scientific matters of M. Homer, Secretary and Treasurer of the Con- 

 struction Company, we have been furnished on three occasions with 

 specimens of these shells, which he specially and personally col- 

 lected on his visits to the field of operations. 



It is the purpose of this paper to put on record the species of 

 these shells and also of the marine diatoms which were associated 

 with them in the same matrix, and to indicate, though perhaps ten- 

 tatively, from a study of both the macroscopic and microscopic fos- 

 sils, the geological age of the bed from which they were obtained. 



The Dismal Swamp Canal connects on the south at a point near 

 South Mills, N. C, with the headwaters of the Pasquotank River, a 

 tributary of Albemarle Sound, and on the north at a point near 

 Deep Creek with the waters of the south branch of the Elizabeth 

 River, a tributary of the James River and the Chesapeake Bay. 

 The general direction of the canal between these two points is north- 

 ward, with, however, a decidedly obtuse angled bend, or bow, to the 

 westward, the angle being near Drummond Lake, from which a 

 feeder canal brings the water from the Jake into the main canal. 

 This feeder was also deepened. 



M. Homer states that the shells furnished by him were obtained 

 from the following localities : — 



