Whenever a claim petition or other petition is presented to the board, the board shall, by general rules or special order, either direct it to be heard by one or more members of the board or assign it to a referee for hearing: Provided, however, That petitions presented under sections four hundred and eleven and four hundred and twelve¹ shall be heard by one or more members of the board.

The department shall serve upon each adverse party a copy of the petition, together with a notice that such petition will be heard by the board or the referee to whom it has been assigned (giving his name and address), as the case may be, and, if the petition shall have been assigned to a referee, shall mail the original petition to such referee, together with copies of the notices served upon the adverse parties.