1. Use semicolons (;) to separate items in a series when those items contain commas.

      Meanwhile, the natural forces on the planet Vogsphere had been working overtime to make up for their earlier blunder. They brought forth scintillating jewelled scuttling crabs, which the Vogons ate, smashing their shells with iron mallets; tall aspiring trees with breathtaking slenderness and colour which the Vogons cut down and burned the crab meat with; elegant gazelle-like creatures with silken coats and dewy eyes which the Vogons would catch and sit on.
      1. You can, but usually shouldn’t, use a semicolon to join two independent clauses without using a conjunction.

        They never evolved again; they should never have survived.