The garden variety horizontal flute or cove below the topline of the comb is not identical to the little fillip on the Lefevers. The first follows naturally from an attempt to "thin" the thumbhole area just above the wrist and extend the topline of the wrist as a "shadow" line onto the stock. The diagonal indent on the Lefevers is a distinct feature with the purpose of placing a bead or button on the end of the comb. The lighting in Silver's photo could not make this any clearer.

jack