Section 7. The clerk of the courts for the county in which an indictment for a capital crime has been entered, or, in the county of Suffolk, the clerk of the superior court for criminal business, shall forthwith send notice thereof, with a copy of the indictment, to the chief or first justice of the court and to the attorney general. Any justice of said court may thereupon appoint a time for the arraignment of the prisoner, which shall take place either at a regular sitting or on a day specially assigned therefor.