DESCRIPTION. 



Variety, c. Shell conic, turreted, imperforate, white, 

 immaculate : whorls from six to eleven, touching each oth- 

 er only by the ribs, but with a very narrow^ interval : riba 

 nine to each volution, prominent, simple, a little oblique, 

 somewhat recurved and with a more or less obvious, ob- 

 tuse angle or shoulder above near the suture : aperture 

 oval-orbicular : base a little angulated : labium distinct. 



Length from three-fifths to nearly nine-tenths of an 

 inch. 



OBSERVATIONS. 



Inasmuch as the European specimens of clathrus in my 

 collection are almost all coloured, spotted or banded and 

 destitute of any obvious angle or shoulder on the ribs near 

 the suture, and the suture is somewhat more contracted, 

 I was led to describe this as a distinct species under the 

 name of angulafa ; but as the clathrus is often, and per- 

 haps usually, destitute of colour, and our specimens fre- 

 quently occur without much appearance of the angle of 

 the ribs, I have judged it prudent to place it as a variety of 

 the clathrus, though I propose that it be separated under 

 the above name. Lamarck describes a variety b., and al- 

 though he quotes the true Linna^an name of clathrus, yet 

 he has placed the species under a new name, which agree- 

 ably to our principle relative to the exclusive right of pri- 

 ority of description, wc cannot admit, notwithstanding the 

 fact, that the word clathrus may apply equally well to oth- 

 er species. 



