199 



at the finaller end, longer tlian the others near it: colour 

 opaque-brown. Length more than one eighth of an inch. 



This fliel!, which we received from Mr. Boys, differs 

 from A^. fuharcuatus in being longitudinally (Iriated, or 

 ridged : in other refpeds the (liape is fimilar to the variety 

 defcribed, of that fpecies. 



We are inclined to think this may be a variety of the 

 N. ohliquus of thofe authors quoted : the only difference 

 appears to confifl in that being truncated at the anterior 

 end, and crenated round the margin, inflead of being pro- 

 duced to a conic fyphon. Such a variety would not be 

 more extraordimry, if we confider the variation incident 

 to the A^. Radicula : and indeed, the figure of the A^. ol^li- 

 quus, given hv M a rtini, is exa611y what our fliell would 

 be, if the conic part, of the anterior articulation, was cut 

 off. It is, therefoie, verv probable the A^. ohliquus, as 

 generally defcribed, is nothing more than a variety, or 

 more probably a mutilated fpecimen, of this (hell. 



N. with a flrait, fub-cvlindric fhell, a little tapering ; Costatus. 

 with twelve raifed articulations, furniflied with four equi- Tab. 14. f. 

 diRant, flrong, longitudinal ribs, running the whole length 

 of the fhell : aperture extended in a come fyphon. Length 

 a quarter of an inch. 



Mr. Boys favoured us with an excellent drawing of 

 this new, and curious fhell, found on the coafl of Kent: 

 and with it, a variety with only fix joints. 



