Despite a reasonably solid premiere, the Fox Children’s Network will pull its new animated series “The X-Men” after tomorrow’s airing and won’t bring the show back until January.In the interim, Fox has acquired rights to air off-net episodes of “Mighty Mouse,” the Ralph Bakshi-produced animated revival that aired a few seasons back on CBS. “X-Men,” based on the popular Marvel Comics heroes, is a pet project of FCN president Margaret Loesch, who was president of Marvel Prods. before joining Fox. Produced by Saban Entertainment and CND in association with Marvel Prods., “X-Men” will air the second half of its two-part premiere but then disappear until Jan. 9, when Fox will repeat the first two episodes before starting with new shows the following week. The first episode, which aired Oct. 31, drew an OK 3.6 rating, 12 share in households and similar numbers among kids age 2-11, but it also attracted a whopping 44 share of male teens.