Any action to establish a metropolitan district shall be initiated by a two-thirds vote of the legislative body of the central city and of any one or more towns, cities or boroughs in the metropolitan area, or by petition filed with the clerk of any such municipality for submission to the legislative body and signed by not less than ten per cent of the electors of such town, city or borough wishing to form a metropolitan district. Upon the filing of such petitions, the clerk with whom the petitions are filed shall proceed forthwith to determine the sufficiency thereof by comparing the signatures thereon with the names contained in the registry list of the municipality in which the petition has been circulated.