A member of the city retirement system who was in public service with a public agency whose functions were assumed by the city and who was thereby transferred to and became an employee of the city may elect by written notice filed with the retirement system manager to make contributions pursuant to this section and to receive credit in the retirement system for all or any part of his or her allowed public service time with the public agency. Such election must be made within ninety (90) days of the date of his or her employment with the city or prior to July 20, 1968, whichever is later. Upon affirmative election, payment of a lump sum contribution shall be made immediately, or by payroll deductions commencing on first payroll thereafter. (Prior code § 34.08.800)