  Three-stage $t$-tests of separated one-sided hypotheses are derived,
extending Lorden's optimal three-stage tests for the one-dimensional
exponential family by using Lai and Zhang's generalization of Schwarz's optimal
fully-sequential tests to the multiparameter exponential family. The resulting
three-stage $t$-tests are shown to be asymptotically optimal, achieving the
same average sample size as optimal fully-sequential tests.
