Extending Sparks’s theorem, we determine the cardinality of the lattice of \((C_1,C_2)\) -clonoids of Boolean functions for certain pairs \((C_1,C_2)\) of clones of Boolean functions. Namely, when \(C_1\) is a subclone (a proper subclone, resp.) of the clone of all linear (affine) functions and \(C_2\) is a subclone of the clone generated by a semilattice operation and constants (a subclone of the clone of all 0- or 1-separating functions, resp.), then the lattice of \((C_1,C_2)\) -clonoids is uncountable. Combining this fact with several earlier results, we obtain a complete classification of the cardinalities of the lattices of \((C_1,C_2)\) -clonoids for all pairs \((C_1,C_2)\) of clones on \(\{0,1\}\) .