 The Millian view may be called direct reference (Kaplan 1977), since the reference of singular proper name is not mediated by a connotation/sense/intension. The semantic value of such a name just is the individual to which it refers. Such terms are thus rigid designators—they denote the same object with respect to all possible worlds (Kripke 1980, 48). How does this view extend to natural kind terms? The answer is that the view does not transfer if we take the analogue of the denotation of a singular term to be the extension of a kind term. This is because presumably the extension of a kind term differs from world to world, since the individual members of a kind, such as individual tigers and lumps of gold, are generally contingent entities.