Dear Rachel:

The best and most comprehensive book on the history of shell collecting is
A History of Shell Collecting by S. Peter Dance (E. J. Brill, 1986).

There is also Rare Shells, by S. Peter Dance (Faber & Faber, 1969).

Two books with some material on the history of collecting shells:

Possessing Nature: Museums, Collecting, and Scientific Culture in Early
Modern Italy by Paula Findlen (U. of Cal. Press, 1994).

Collector and Curiosities: Paris and Venice, 1500-1800 by Krzysztof Pomian
(Polity Press, 1990).

Hope this helps.

Sincerely,
Stephen E. Pober