In Commonwealth v. Clemmons, supra at 291, we inferred that a trial on the merits was being held where the judge gave no indication that he might decline jurisdiction, and where the defendant had every reason to believe that a trial was being conducted. See Commonwealth v. Mesrobian, 10 Mass. App. Ct. 355 (1980); Commonwealth v. Crosby, 6 Mass. App. Ct. 679 (1978). The Commonwealth argues that the instant case is distinguishable because two factors served to put the defendant on notice that a probable cause hearing was being conducted.

The erroneous dismissal aside, any judicial determination that the charges against the defendants were to be tried in the Superior Court should have been preceded by a "bind-over" or probable cause hearing and an unambiguous declination of jurisdiction with respect to those charges within the District Court's final jurisdiction. See G.L.c. 218, § 30; District/Municipal Court Rules of Criminal Procedure 4(f) (1996); Commonwealth v. Mesrobian, 10 Mass. App. Ct. 355, 357 (1980). We discern no merit in the contention of the defendants that the Commonwealth's failure to appeal from the dismissal of the original complaints is a bar to a review in this court of the dismissal of the new complaints.

It was possible for the District Court judge to exercise final jurisdiction over all charges, with the exception of the trafficking complaints. The importance of a District Court judge announcing "unambiguously" at the outset his or her intention to decline or accept final jurisdiction over an offense that is within the concurrent jurisdiction of the District Court was highlighted in Commonwealth v. Mesrobian, 10 Mass. App. Ct. 355, 357 (1980). That election is decided by the judge, not the prosecutor.