  We present a measurement of the $\ttbar$ production cross section using $194
\mathrm{pb^{-1}}$ of CDF II data using events with a high transverse momentum
electron or muon, three or more jets, and missing transverse energy. The
measurement assumes 100% $t\to Wb$ branching fraction. Events consistent with
$\ttbar$ decay are found by identifying jets containing heavy flavor
semileptonic decays to muons. The dominant backgrounds are evaluated directly
from the data. Based on 20 candidate events and an expected background of
9.5$\pm$1.1 events, we measure a production cross section of
$5.3\pm3.3^{+1.3}_{-1.0} \mathrm{pb}$, in agreement with the standard model.
