Hi from finally raining in St. Louis,

Question:   Do the publication dates for the three Sowerbys
overlap each other?   In doing some work this afternoon, I think I found an author as "Sowerby, 1842"  but then found a different
shell with the author as "Sowerby II, 1842."    Do these both
exist, or should they both be Sowerby II, as the descriptions have the same date?

Thanks,
Linda