  A search for Theta^+(1540) and Xi^{--}_{3/2}(1862) pentaquark candidates has
been performed in proton-induced reactions on C, Ti and W targets at sqrt(s) =
41.6 GeV studying the pK_s resp. Xi^-pi^- and Xi^-pi^+ (and charge conjugated)
decay channels at mid-rapidity. With sensitivities of (Br)x(dsigma/dx_F) < 5 to
25 microbarn/nucleon, we find no evidence for narrow pentaquark peaks in any of
the studied final states. Preliminary values for the upper limit of relative
yield ratios at mid-rapidity are (Theta^+(1540)) / (Lambda(1520)) < 0.02,
(Br)x(Xi^{--}_{3/2}(1862)) / (Xi(1530)^0) < 0.077, and
(Br)x(Xi_bar^{++}_{3/2}(1862)) / (Xi_bar(1530)^0) < 0.058 at 95% CL.
