def __look_up_geom(self, geomType):
        """ compares the geometry object's type verse the JSOn
            specs for geometry types
            Inputs:
              geomType - string - geometry object's type
            Returns:
               string JSON geometry type or None if not an allowed type
        """

        if geomType.lower() == "point":
            return "esriGeometryPoint"
        elif geomType.lower() == "polyline":
            return "esriGeometryPolyline"
        elif geomType.lower() == "polygon":
            return "esriGeometryPolygon"
        elif geomType.lower() == "multipoint":
            return "esriGeometryMultipoint"
        else:
            return None