Italian Giovanni Brocchi (1772–1826) was a geologist and mineralogist, interested in natural history. Unlike Lamarck, Brocchi saw species as discrete and fundamentally stable unless driven to extinction by external forces. Brocchi thought that new species replaced extinct ones.
Brocchi’s book on evolution was read by Darwin when he was a student at Cambridge. Influenced by Brocchi, Darwin’s 1st hypothesis of species origin was explicitly saltational, invoking geographic isolation as provoking abrupt appearance of a new species. Darwin later rejected saltation.