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Cabinet of the Acad. Nat. Sciences, No. 823. 



OBSERVATIONS. 



When taken alive, in favourable situations, this 

 shell exhibits a beautiful straw-coloured epidermis, 

 wrinkled at each end, where it is dark greenish 

 brown, and crossed by irregular hair-like lines; a 

 few parrallel green lines cross the centre of the valves, 

 and appear like scratches in the shell when divested 

 of its epidermis. 



I have figured and described this species as we find 

 it upon the New Jersey coast, and it will be seen by 

 a reference to the figure in the Encyclopedie JSieth- 

 odique, that it diiFers considerably in outline from the 

 shell described by Lamarck as inhabiting the ocean of 

 the Antilles : in the latter the beaks are central, whilst 

 in the northern variety they are considerably behind 

 the centre, and the shell is larger and higher in pro- 

 portion to the length ; these differences might lead 

 us to regard it as a distinct species, did we not ob- 

 serve intermediate varieties from East Florida, which 

 leave no room to doubt their specific identity. 



My friend Dr. S. G. Morton has sent me the fol- 

 lowing interesting notice of this species: 



^^It is found in great numbers at Great Egg Har- 

 bour on the coast of New Jersey. The most beauti- 

 ful specimens inhabit the Rainboiu A«r, a jandy shoal 

 exposed at low tide. There is not, in common, any 

 perforation of the sand to indicate the presence of 

 this species, and, in order to detect it, the surface 

 must be removed to the depth of three or four inch- 

 es. These excavationg, if carefully made, expose a 



