All that area south of a line commencing at a point due west of the end of Glenwood Avenue (City of Yonkers) on the east bank of the Hudson River; thence due east to Glenwood Avenue; thence easterly along Glenwood Avenue to Lake Avenue; thence easterly along Lake Avenue to Nepperhan Avenue; thence northerly along Nepperhan Avenue to Old Nepperhan Avenue; thence easterly along Old Nepperhan Avenue to Saw Mill River Road; thence northerly along Saw Mill River Road to the Saw Mill River Parkway; thence southerly along the parkway to Yonkers Avenue; thence easterly along Yonkers Avenue to Mount Vernon Avenue; thence easterly along Mount Vernon Avenue to Lincoln Avenue; thence easterly along Lincoln Avenue to North Avenue (City of New Rochelle); thence due east to the New England Thruway; thence northeasterly along the New England Thruway to the Mamaroneck village line; thence clockwise along the village line to Long Island Sound.