Three new BL Lacertae objects in the Palomar-Green survey

We have identified three BL Lacertae objects in the Palomar-Green Survey which were previously misclassified as DC white dwarfs, namely PG 1246+586, PG 1424+240, and PG 1437+398. Our reclassification is based on the detection of these objects as x-ray sources in the ROSAT all-sky survey and upon our subsequent detection of intrinsic linearly polarized and variable optical emission from these sources. As a result of the ROSAT survey, the number of identified BL Lac objects in the Palomar-Green catalog of UV excess objects has been doubled. Corrected optical positions are presented for PG 1246+586 and PG 1437+398.