Hi James,
Yes, the Scissurellidae do look like small Pleurotomaria shells - VERY small,
usually about 2 to 4 mm.  They do have the same sort of "slit" as the
Pleurotomariidae.  They are seldom offered for sale, and when they are, they
tend to be a bit pricey for minishells, usually in the $10.00 to $20.00 range.
Kay Vaught, in her A Classification of the Living Mollusca, puts both these
families in the same superfamily (Pleurotomarioidea), along with the
Haliotidae (abalones).
Paul M.