128 PROCEEDINGS OF THE ACADEMY OP 



of this species, as of Amphidesma consfricta, are not certainly- 

 recent, being only single valves. Of the beautiful Tellidora lunii- 

 lata we obtained several living examples, some attaining a length 

 of nearlj'^ two inches. Among the shells of a tropical character 

 several species will be noticed which have not hitherto been found 

 north of the West Indies, and do not exist upon the South Caro- 

 lina coast." 



Beaufort, Fort Macon, and the Morehead Depot are nearly 

 equidistant, and about two miles from each other. Vessels 

 of ordinary tonnage reach Morehead by the nearly direct ship- 

 channel, but none larger than schooners of the lightest di'aught 

 can reach Beaufort, between which and Fort Macon lies a small 

 island. The entrance to the harbor is comparatively narrow ; and 

 as a large body of water passes through it twice a day, the cur- 

 rent in the main channel is strong. This sweeps sharpl}'^. close past 

 the projecting extremity of Bogue Banks, but its erosive action 

 seems to be about counterbalanced by that of the S. to W. winds 

 which almost constantly prevail, depositing sand as fast as it is 

 removed. I can account only in this way for the permanence of 

 this, the most exposed point in the harbor. The waters that 

 pass through the main outlet are collected from several widely 

 separated directions from E. through N. to W. ; and this is one 

 evident cause of the numerous shoals that now obstruct the har- 

 bor, deflecting the different currents, and increasing as well as 

 continually varying their conflict with each other. As a result, 

 the hj'drography of the harbor is notably inconstant, and surveys 

 can be relied on in detail only for comparatively short periods. 

 The channels and minor water-lines are especially susceptible of 

 change, because the land consists almost entirely of loose sand. 

 No better illustration of general instability is required, than the 

 present condition and situation of what was once the site of Foi't 

 Hamilton ; now a slight shoal indicated b}^ breakers between Fort 

 Macon and the western point of Shackleford, nearly a mile from 

 the present Fort. This last has only been preserved from the en- 

 croachment of the sea, which once washed the base of the glacis, 

 by a system of stone breakwaters laid down on the outer beach, 

 which have carried the water-line outward one or two hundred 

 yards. Details of the contour of the beach change noticeably 

 with every considerable storm; and within the harbor, the shoals 

 have very perceptibly varied in extent and shape during the short 



[July 18, 



