A new electronic transition of SiH has been observed in absorption near 1907 Å in flash discharges through mixtures of SiH4 and H2. The rotational analysis shows this transition to be of the type 2Σ+−2Π. The corresponding transition of SiD has also been observed and analyzed. The D2Δ−X2Π transition near 2058 Å which was observed and analyzed by Verma in SiD has been measured here for SiH, where the lines are much broader on account of predissociation. The predissociation phenomena in SiH and SiD and the electron configurations are briefly discussed, and the presently known molecular constants of these molecules are summarized.