336 On the Secondary and Tertiary Formations. 



promiscuously together in great confusion ; single valves of the 

 bivalves are more frequently found than the two together, and 

 even the stronger univalves are most often seen in fragments. 

 So abundant are they, that in cleaning out some of the larger 

 shells a great number of small and more perfect specimens were 

 found in their interior, and added to my collection. A Pectun- 

 culus quinque-rugatus, in particular, enclosed between its two 

 valves a multitude of shells and fragments closely imbedded in 

 a fine clear quartz sand. The contents when picked out occu- 

 pied a space full twice that in which they were so closely 

 packed. Although the diameter of the Pectunculus was only 

 two inches and one fourth, there were in it a Cytherea reporta, 

 beautifully preserved with its natural polish, one and one third of 

 an inch long, and itself filled with other smaller shells and a 

 purer sand than that which surrounded it — several small Ostreae, 

 CorbulEe, and duplicates of twenty or thirty other species. There 

 are, as seen by the accompanying catalogue, about SO species 

 found at this locality. Of these 12 are recent, and 20 at least 

 heretofore undescribed. Some yet undetermined remain in the 

 hands of Mr. Conrad, and of these only the genera are given. 

 The Oliva idonea has been previously described by Mr. Conrad ; 

 it is one of the most beautiful shells found here, being finely 

 preserved, and most of the specimens not having lost their nat- 

 ural polish. The people living in the neighborhood know them 

 by the name of " key shells," from their procuring them to attach 

 to a bunch of keys. The cones are of the species adversai'itis, 

 so named from their being nearly all reversed ; one of mine is 

 the only exception known. The bivalves are only occasionally 

 met with entire. 



It is remarked that the water in the well never varies in fresh- 

 ets nor droughts, and tales are told of ineffectual attempts hav- 

 ing been made to sound it, and of a strong current setting 

 through it, sucking down whatever is thrown in ; that there is a 

 current I doubt not, it being nothing unusual for a stream of 

 water to sink suddenly under ledges of limestone, as at the 

 Eutaw springs in South Carolina, and the limestone of the sec- 

 ondary formation I believe to be not far below the surface of the 

 water, perhaps directly under the blue sandstone at the surface, 

 which is very likely the upper rock of that formation, and the 

 blue clay the lowest of the middle tertiary, as it often is, (the 



