§ 70. Opposing creditor to file proofs, if not named in schedule. Where the name of an opposing creditor does not appear in the schedule, he must file, with the specification of his objections, proof, by affidavit, that he is a creditor; and, if his debt is not set forth in the schedule, he must also file his affidavit, to the effect specified in subdivisions first and second of section sixty-one of this chapter.