Pub. Util. Code, § 2939

In any city and county having a board of election commissioners and a registrar of voters, the clerk of the legislative body thereof shall immediately upon the filing of any petition with him, transmit the petition to the board of election commissioners, who shall forthwith deliver the petition to the registrar of voters, who shall perform all the duties herein required to be performed in other municipal corporations by the clerk of the legislative body respecting the examination and certification of the petition. The registrar of voters shall, upon making his certificate, forthwith return the petition to the clerk, who shall thereupon present the petition and the attached certificate to the legislative body of the municipal corporation as provided in this article.