Does anyone know the difference between the Northern Whelk (Common Northern Buccinum--Buccinum undatum) and Plectrum Buccinum (Sinuos Whelk-Buccinum Plectrum)? What is the range of the Plectrum? I think I have one of each, but it's hard to find anything on the Plectrum.

I worked this up so those of us unfamiliar with these species could see what the discussion is about.

Thanks Marlo. They are very similar, but your photos show that I do in fact have examples of both. The undataums I found on the NE U.S. coast up to Canada. The 2 plectrums were found on the South coast of Labrador and Arctic coast of Norway.