The study of partial clones on 2 := {0, 1} was initiated by R. V. Freivald. In his fundamental paper published in 1966, Freivald showed, among otherthings, that the set of all monotone partial functions and the set of all self-dual partial functions are both maximal partial clones on 2. Several papers dealing with intersections of maximal partial clones on 2 have appeared after Freivald work. It is known that there are infinitely many partial clones that contain the set of all monotone self-dual partial functions on 2, and the problem of describing them all was posed by some authors. In this paper we show that the set of partial clones that contain all monotone self-dual partial functions is of continuum cardinality on 2.