A GROUP of Senegalese dancers who vanished after a performance in Berkely in the United States still had not been heard from on Thursday by the promoters who backed their US tour. More than half the members of Ballet d’Afrique Noire apparently opted to slip into the anonymity of the San Francisco Bay Area’s multi-ethnic population on Sunday rather than finish the last week of their US tour and then return to their homeland in West Africa. Dance promoters and officials from the Immigration and Naturalization Service believe the 17 Senegalese dancers who disappeared from the Durant Hotel near the University of California, Berkeley, plan to seek asylum in the Bay Area. Ballet d’Afrique Noire was established in 1958 and is one of the oldest folk dance companies in Senegal.