Add Layers from WMS (explicit source)
    var options = {'transparent': true}; //,'identify': false
    var source = L.WMS.source("http://www.***.com/arcgis/rest/services/SCP/WMSMap/MapServer", options);
    var layer1 = source.getLayer('2');
    var layer2 = source.getLayer('3');
    var layer3 = source.getLayer('6');

    var baseLayers = {
    'Street Map': mapnikLayer,
    'Black and Whilte': blackAndWhite,
    'Bing Aerials':bing
    }
    //Add Overlays of Selectable Layers
    var overlays = {
    'Cities': cities,
    'layer1 ': layer1 ,
    'layer2 ': layer2 ,
    'layer3 ': layer3
    }

    L.control.layers(baseLayers, overlays).addTo(map);
    var control = L.control.selectLayers(baseLayers, overlays)
    control.addTo(map)