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proceedings of the [March, 1858. 



little longer than the shell, narrow, wider in front; posterior end 

 quite narrow, but not pointed ; operculum small, on posterior end 

 of foot; head projecting from the foot, with tentacles one-third the 

 length of the shell, very delicate, almost hair-like, with small 

 black eyes at the base. Animal active, keeping the proboscis in 

 constant motion, while the tentacles are little used. 



This shell is like the Nassa lunata, Say, but it is narrower in 

 proportion to its length ; the aperture is shorter and differently 

 shaped, the pillar being straighter, and the denticulations of the 

 outer lip stronger than in the N. lunata. 



The animals differ; the tentacles of the C. spirantha are delicate 

 and hair-like, while in the N. lunata they are rather thick for the 

 size of the animal. 



I have only found this shell in Wando River, near the village 

 of Cainhoy- — on oyster shells about low-water mark — not com- 

 mon. 



Prof. L. R. Gibbes made an oral communication on some 

 plants from the neighborhood of Bluffton, S. C, also on half- 

 formed sandstone, lying on plufT mud. 



Prof. J. McCrady made some remarks on the Eocene forma- 

 tion in the neighborhood of Alligator, Florida. 



Mr. McCrady said that in a recent visit to Alligator, Florida, 

 he had collected the fossil echinoderms which he presented at this 

 meeting. The soil in this region was chiefly sandy, and under it 

 was a calcareous marly rock, which being continually worn by 

 percolation of water, frequently sunk in, forming usually more or 

 less circular depressions in the sandy soil, which are known both 

 in this State and in Florida as sinks. These appeared usually to 

 arrange themselves in tolerably continuous lines, thus suggesting 

 the idea that they follow the course of subterranean streams. He 

 was told that instances of streams disappearing suddenly under- 

 ground after running a portion of their course on the surface, were 

 known. And it was affirmed of one of the smaller tributaries of 

 the Suwannee, that it disappeared in this manner, emerging again 

 at the distance of a mile or more from its point of disappearance. 

 An instance of a stream disappearing in this manner for a short 

 distance underground, was known in our own State, at Eutaw 

 Springs, the scene of one of our Revolutionary battles. The sinks 

 before mentioned were frequently filled with water, and there were 

 quite a number of lakes stocked with fresh water fish, which fre- 



