 public extension Geometry {
     /** @name Topological properties */
     
-    /** Returns a ShapeKitPolygon that represents all points whose distance from this geometry is less than or equal to the given width.
+    /** Returns a Polygon that represents all points whose distance from this geometry is less than or equal to the given width.
     */
     func bufferWithWidth(width: Double) -> Polygon {
         let bufferGEOM = GEOSBuffer_r(GEOS_HANDLE, self.geometry, width, 0)

        return envelope
    }
    
    /** Returns a ShapeKitPolygon that represents the bounding envelope of this geometry. */
    func pointOnSurface() -> Point {
        let pointOnSurfaceGEOM = GEOSPointOnSurface_r(GEOS_HANDLE, self.geometry)
        let pointOnSurface = Geometry.create(pointOnSurfaceGEOM, destroyOnDeinit: true) as! Point

        return convexHull
    }
    
    /** Returns a Polygon that represents the bounding envelope of this geometry.
    */
    func envelope() -> Polygon {
        let envelopeGEOM = GEOSEnvelope_r(GEOS_HANDLE, self.geometry)
