416 PROCEEDINGS OF THE ACADEMY OF [1898. 



The Croatan beds are in North Carolina, about 120 miles slightly 

 west of south of the Dismal Swamp, and about eighteen miles from 

 the nearest point on the coast. They are on the northern border 

 of a similar swamp area on the southern side of the Neuse River, 

 and are about fifteen miles below Newbern. Both the Croatan 

 and the Dismal Swamp shell localities are approximately 75 or 80 

 miles eastward of the rocks of the Piedmont plateau, which rocks 

 bound the inland border of the less consolidated beds of the Atlan- 

 tic Coastal plain. The two localities occupy a similar position both 

 geographically and stratigraphically. 



The Waccamaw beds are in the extreme eastern part of the State 

 of South Carolina, and are exposed along the banks of the Wacca- 

 maw River from some four miles, to about 18 miles above Conway. 

 They are on low ground, and are also on the western side of another 

 of the swamp areas that occur on the seaward margin of the coastal 

 plain from Cape May County, N. J., to South Carolina and Georgia. 

 Geographically, they are similarly situated to the Croatan and the 

 Dismal Swamp localities. 



Fossil mollusks from the Croatan and the Waccamaw localities 

 have been carefully studied and listed I y Dr. W. H. Dall, who refers 

 both beds to the Pliocene. The fauna, however, when considered 

 with reference to the percentage of recent over extinct forms, would 

 indicate that the Croatan beds were slightly the younger of the two 

 deposits, there being, according to Dr. Dall, 83 per cent, of recent 

 forms in the Croatan and only 70 per cent, in the Waccamaw beds. 

 In summing up, Dr. Dall says " the Croatan beds are obviously 

 newer than those of the Waccamaw, yet when compared with the 

 admitted Pleistocene beds of South Carolina" such as those of Sim- 

 mons Bluff, the presence on the Neuse " [the locality of the Croatan 

 beds] " of 41 out of 90 species, which have not been known later 

 than the Pliocene, forbids us to regard the fauna as later than Plio- 

 cene." 



In the study of the mollusks from the Dismal Swamp Canal the 

 writer has had the advantage of some correspondence with Dr. W. 

 H. Dall and of consultation with Prof. H. A. Pilsbry and C. W. 

 Johnson, the latter of whom has collected a full series of shells from 

 the Croatan beds, and a like series from the Waccamaw beds, both 

 of which collections are now displayed in the Museum of the 

 Wagner Free Institute of Science of Philadelphia, and with which 

 the shells from the Dismal Swamp have been carefully compared. 



