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October 15, 1851. 



Dr. A. A. Gould in the Chair. 



The Secretary read a letter from the President in reply 

 to the resolution passed at the preceding meeting, greeting 

 him on his return from Europe. It contained gratifying 

 assurances of the estimation in which the Society is held 

 abroad, and of his own continued interest in its welfare. 



Mr. William Stimpson read a monograph of the genus 

 CcBCum in the United States. 



This genus, belonging, as is shown by the animal, to the 

 TurritellidcE, is remarkable for the form of the shell, which 

 approaches that of Dentalium. This has occasioned the general 

 misapprehension of its true position which has existed among 

 authors, until the animal was first examined, three years ago, by 

 Mr. Clark, of Exmouth, England. The genus has not been 

 before noticed as occurring on our coast. 



C. NiTiDUM. Shell arcuated, thin, pellucid ; surface white, 

 shining, glabrous, with indistinct strise of growth ; aperture very 

 oblique, in diameter about two thirds that of the shell at its 

 broadest part, which is at the middle. The shell is contracted 

 at its posterior extremity. Thus the inner outline is much 

 shorter and less curved than the outer one. Long. .075 ; lat. 

 .025 poll. Hah. Florida. 



C. Floridanum. Shell much arcuated, somewhat thick, 

 white, shining; with about thirty-two sharp, elevated ribs, much 

 narrower than their interspaces. Aperture slightly oblique, not 

 contracted. In some specimens there is a broad rib just above 

 the aperture. Long. .075 ; lat. .02. poll. Hab. Florida. 



C. PULCHELLUM. Shell, in its adult state, clavate, arcuated, 

 contracted at both extremities, and having a somewhat angular 

 appearance at its outer or dorsal outline, which is much longer 

 than the inner. It is somewhat thick and strong, of a pale 

 yellowish-brown color, and sculptured with about twenty-five 



