100 GENUS BUCCINUM. 
are the only sure guides, for the formation of groups, and their 
natural approximation. This is the principle which I have 
adopted, as establishing with most precision, those of the genus 
I have just described. I have pointed out in my table by a 
bracket, the species, which I think ought to be united, and 
form only: varieties. 
Norse. ‘The following American species, not found in Kiener, together 
with the volumes in which they have been described, are here mentioned, 
for the convenience of our Conchologists. 
Buccinum ornatum, Say. Described in Journal of the Academy of Na- 
tural Sciences of Philadelphia, vol. 2, p. 229. 
Nassa vibex, Say. J. A. N. 8., vol. 2, p. 231, and American Conch., 
No. 6, pl. 57, fig. 2. 
N. trivittata, Say. J. A.N.S., vol..2, p. 231. 
N. acuta, Say. J. A. N. §., vol. 2, p. 234, and American Conch., No. 
VI, pl. 57, fig. 3. 
N. unicincta, Say. J. A. N.S., vol. 5, p. 212, and American Conch., 
No. VI, pl. 57, fig. 1. 
N. alba, Say. J. A.N.S., vol. 5, 212. 
N. lunata, Say. J. A.N.S, vol. 5, 213. 
