1. Every municipality with a population of less than four hundred thousand which makes provision for a municipal judge or judges shall notify in writing the circuit clerk of the county in which the municipality or major geographical portion thereof is located before the municipal judge or judges hear and determine any cases; provided, however, that until March 1, 1979, municipal judges may hear and determine cases prior to such notification.

2. Judges of municipal courts in office on January 1, 1979, may serve out the terms which they are then serving as municipal judges of the circuit court if the municipality makes provision for the office of a municipal judge even though such judge may not meet the requirements of subsections 3, 7 and 8 of section 479.020.

3. Each judge of a municipal court in a city with a population of over four hundred thousand who is in office on January 1, 1979, and who is a full-time judge, shall become a municipal judge for that city without action being required on the part of the city, shall serve out the term for which he was selected, and subject to the provisions of chapter 479, shall be eligible for retention in office at the end of such term under the provisions of any plan of merit retention for municipal court judges in effect on January 1, 1979, which shall be deemed to be continued in effect without action on the part of the city.