Tramp: how to set path to remote shell?

[Ethan]

The path to my shell on my local machine is /bin/bash.  When
attempting to bring up a shell on the remote machine I get the error:

exec: /bin/bash: not found

Process shell<2> exited abnormally with code 127


It seems that tramp is using the path from my local machine as the
path on the remote machine.  The actual remote machine path for bash
is /usr/local/bin/bash.  Does anyone know which variable to set so
that tramp uses the correct path to bash on the remote machine?   I
did RTFM, but didn't find it.

Thanks.