Section 6. The court shall have original jurisdiction of all crimes. Crimes committed in that part of Scituate described in chapter three hundred and ninety-four of the acts of nineteen hundred and twelve shall be within the territorial jurisdiction of the court both in Norfolk county and in Plymouth county, and arrests and service of process in such cases may be made by an officer qualified to serve criminal process in Cohasset. Crimes committed in any part of Cambridge, Watertown or Newton lying in the Charles river basin shall be within the territorial jurisdiction of the court both in Middlesex county and in Suffolk county.