Does a jury need to agree unanimously on the act constituting the basis of a guilty verdict?

Defendant contends the court committed reversible error in failing to instruct sua sponte that the jury must unanimously agree on the particular act constituting the basis for its guilty verdict on each charge involving Penal Code section 647a (child annoyance or molestation). This contention raises two distinct problems: (1) whether a unanimity instruction was required by the evidence that defendant exposed himself to each victim on more than one occasion, and (2) whether such an instruction was required by the evidence that defendant also lifted the shirt or blouse of each 647a victim except one and touched her chest with a stethoscope. As to the first problem we conclude no such instruction was required. As to the second we conclude that even if such an instruction was required, its omission was harmless beyond a reasonable doubt. (See People v. Gordon (1985) 165 [185 Cal.App.3d 1014] Cal.App.3d 839, 855, 212 Cal.Rptr. 174 and cases there cited.) We consider first the problem of the evidence of repeated genital exposure.